summaryrefslogtreecommitdiffstats
path: root/layout/base/nsIPresShell.h
blob: 4016cc0a992551a984e907c040ddbce52b11799e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * This Original Code has been modified by IBM Corporation.
 * Modifications made by IBM described herein are
 * Copyright (c) International Business Machines
 * Corporation, 2000
 *
 * Modifications to Mozilla code or documentation
 * identified per MPL Section 3.3
 *
 * Date         Modified by     Description of modification
 * 05/03/2000   IBM Corp.       Observer related defines for reflow
 */

/* a presentation of a document, part 2 */

#ifndef nsIPresShell_h___
#define nsIPresShell_h___

#include "mozilla/ArenaObjectID.h"
#include "mozilla/EventForwards.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/StaticPtr.h"
#include "mozilla/StyleSetHandle.h"
#include "mozilla/StyleSheet.h"
#include "mozilla/WeakPtr.h"
#include "gfxPoint.h"
#include "nsTHashtable.h"
#include "nsHashKeys.h"
#include "nsISupports.h"
#include "nsIContent.h"
#include "nsISelectionController.h"
#include "nsQueryFrame.h"
#include "nsCoord.h"
#include "nsColor.h"
#include "nsFrameManagerBase.h"
#include "nsRect.h"
#include "nsRegionFwd.h"
#include "mozFlushType.h"
#include "nsWeakReference.h"
#include <stdio.h> // for FILE definition
#include "nsChangeHint.h"
#include "nsRefPtrHashtable.h"
#include "nsClassHashtable.h"
#include "nsPresArena.h"
#include "nsIImageLoadingContent.h"
#include "nsMargin.h"
#include "nsFrameState.h"
#include "Units.h"

class nsDocShell;
class nsIDocument;
class nsIFrame;
class nsPresContext;
class nsViewManager;
class nsView;
class nsRenderingContext;
class nsIPageSequenceFrame;
class nsCanvasFrame;
class nsAString;
class nsCaret;
namespace mozilla {
class AccessibleCaretEventHub;
class CSSStyleSheet;
} // namespace mozilla
class nsFrameSelection;
class nsFrameManager;
class nsILayoutHistoryState;
class nsIReflowCallback;
class nsIDOMNode;
class nsCSSFrameConstructor;
class nsISelection;
template<class E> class nsCOMArray;
class nsWeakFrame;
class nsIScrollableFrame;
class gfxContext;
class nsIDOMEvent;
class nsDisplayList;
class nsDisplayListBuilder;
class nsPIDOMWindowOuter;
struct nsPoint;
class nsINode;
struct nsRect;
class nsRegion;
class nsRefreshDriver;
class nsARefreshObserver;
class nsAPostRefreshObserver;
#ifdef ACCESSIBILITY
class nsAccessibilityService;
namespace mozilla {
namespace a11y {
class DocAccessible;
} // namespace a11y
} // namespace mozilla
#endif
struct nsArenaMemoryStats;
class nsITimer;

namespace mozilla {
class EventStates;

namespace dom {
class Element;
class Touch;
class Selection;
class ShadowRoot;
} // namespace dom

namespace layers {
class LayerManager;
} // namespace layers

namespace gfx {
class SourceSurface;
} // namespace gfx
} // namespace mozilla

// Flags to pass to SetCapturingContent
//
// when assigning capture, ignore whether capture is allowed or not
#define CAPTURE_IGNOREALLOWED 1
// true if events should be targeted at the capturing content or its children
#define CAPTURE_RETARGETTOELEMENT 2
// true if the current capture wants drags to be prevented
#define CAPTURE_PREVENTDRAG 4
// true when the mouse is pointer locked, and events are sent to locked element
#define CAPTURE_POINTERLOCK 8

typedef struct CapturingContentInfo {
  // capture should only be allowed during a mousedown event
  bool mAllowed;
  bool mPointerLock;
  bool mRetargetToElement;
  bool mPreventDrag;
  mozilla::StaticRefPtr<nsIContent> mContent;
} CapturingContentInfo;

// a75573d6-34c8-4485-8fb7-edcb6fc70e12
#define NS_IPRESSHELL_IID \
{ 0xa75573d6, 0x34c8, 0x4485, \
  { 0x8f, 0xb7, 0xed, 0xcb, 0x6f, 0xc7, 0x0e, 0x12 } }

// debug VerifyReflow flags
#define VERIFY_REFLOW_ON                    0x01
#define VERIFY_REFLOW_NOISY                 0x02
#define VERIFY_REFLOW_ALL                   0x04
#define VERIFY_REFLOW_DUMP_COMMANDS         0x08
#define VERIFY_REFLOW_NOISY_RC              0x10
#define VERIFY_REFLOW_REALLY_NOISY_RC       0x20
#define VERIFY_REFLOW_DURING_RESIZE_REFLOW  0x40

#undef NOISY_INTERRUPTIBLE_REFLOW

enum nsRectVisibility {
  nsRectVisibility_kVisible,
  nsRectVisibility_kAboveViewport,
  nsRectVisibility_kBelowViewport,
  nsRectVisibility_kLeftOfViewport,
  nsRectVisibility_kRightOfViewport
};

/**
 * Presentation shell interface. Presentation shells are the
 * controlling point for managing the presentation of a document. The
 * presentation shell holds a live reference to the document, the
 * presentation context, the style manager, the style set and the root
 * frame. <p>
 *
 * When this object is Release'd, it will release the document, the
 * presentation context, the style manager, the style set and the root
 * frame.
 */

class nsIPresShell : public nsISupports
{
public:
  NS_DECLARE_STATIC_IID_ACCESSOR(NS_IPRESSHELL_IID)

protected:
  typedef mozilla::layers::LayerManager LayerManager;
  typedef mozilla::gfx::SourceSurface SourceSurface;

  enum eRenderFlag {
    STATE_IGNORING_VIEWPORT_SCROLLING = 0x1,
    STATE_DRAWWINDOW_NOT_FLUSHING = 0x2
  };
  typedef uint8_t RenderFlags; // for storing the above flags

public:
  /**
   * All callers are responsible for calling |Destroy| after calling
   * |EndObservingDocument|.  It needs to be separate only because form
   * controls incorrectly store their data in the frames rather than the
   * content model and printing calls |EndObservingDocument| multiple
   * times to make form controls behave nicely when printed.
   */
  virtual void Destroy() = 0;

  bool IsDestroying() { return mIsDestroying; }

  /**
   * Make a one-way transition into a "zombie" state.  In this state,
   * no reflow is done, no painting is done, and no refresh driver
   * ticks are processed.  This is a dangerous state: it can leave
   * areas of the composition target unpainted if callers aren't
   * careful.  (Don't let your zombie presshell out of the shed.)
   *
   * This is used in cases where a presshell is created for reasons
   * other than reflow/painting.
   */
  virtual void MakeZombie() = 0;

  /**
   * All frames owned by the shell are allocated from an arena.  They
   * are also recycled using free lists.  Separate free lists are
   * maintained for each frame type (aID), which must always correspond
   * to the same aSize value.  AllocateFrame returns zero-filled memory.
   * AllocateFrame is infallible and will abort on out-of-memory.
   */
  void* AllocateFrame(nsQueryFrame::FrameIID aID, size_t aSize)
  {
    void* result = mFrameArena.AllocateByFrameID(aID, aSize);
    RecordAlloc(result);
    memset(result, 0, aSize);
    return result;
  }

  void FreeFrame(nsQueryFrame::FrameIID aID, void* aPtr)
  {
    RecordFree(aPtr);
    if (!mIsDestroying)
      mFrameArena.FreeByFrameID(aID, aPtr);
  }

  /**
   * This is for allocating other types of objects (not frames).  Separate free
   * lists are maintained for each type (aID), which must always correspond to
   * the same aSize value.  AllocateByObjectID returns zero-filled memory.
   * AllocateByObjectID is infallible and will abort on out-of-memory.
   */
  void* AllocateByObjectID(mozilla::ArenaObjectID aID, size_t aSize)
  {
    void* result = mFrameArena.AllocateByObjectID(aID, aSize);
    RecordAlloc(result);
    memset(result, 0, aSize);
    return result;
  }

  void FreeByObjectID(mozilla::ArenaObjectID aID, void* aPtr)
  {
    RecordFree(aPtr);
    if (!mIsDestroying)
      mFrameArena.FreeByObjectID(aID, aPtr);
  }

  /**
   * Other objects closely related to the frame tree that are allocated
   * from a separate set of per-size free lists.  Note that different types
   * of objects that has the same size are allocated from the same list.
   * AllocateMisc does *not* clear the memory that it returns.
   * AllocateMisc is infallible and will abort on out-of-memory.
   *
   * @deprecated use AllocateByObjectID/FreeByObjectID instead
   */
  void* AllocateMisc(size_t aSize)
  {
    void* result = mFrameArena.AllocateBySize(aSize);
    RecordAlloc(result);
    return result;
  }

  void FreeMisc(size_t aSize, void* aPtr)
  {
    RecordFree(aPtr);
    if (!mIsDestroying)
      mFrameArena.FreeBySize(aSize, aPtr);
  }

  template<typename T>
  void RegisterArenaRefPtr(mozilla::ArenaRefPtr<T>* aPtr)
  {
    mFrameArena.RegisterArenaRefPtr(aPtr);
  }

  template<typename T>
  void DeregisterArenaRefPtr(mozilla::ArenaRefPtr<T>* aPtr)
  {
    mFrameArena.DeregisterArenaRefPtr(aPtr);
  }

  void ClearArenaRefPtrs(mozilla::ArenaObjectID aObjectID)
  {
    mFrameArena.ClearArenaRefPtrs(aObjectID);
  }

  nsIDocument* GetDocument() const { return mDocument; }

  nsPresContext* GetPresContext() const { return mPresContext; }

  nsViewManager* GetViewManager() const { return mViewManager; }

  nsRefreshDriver* GetRefreshDriver() const;

#ifdef ACCESSIBILITY
  /**
   * Return the document accessible for this pres shell if there is one.
   */
  mozilla::a11y::DocAccessible* GetDocAccessible() const
  {
    return mDocAccessible;
  }

  /**
   * Set the document accessible for this pres shell.
   */
  void SetDocAccessible(mozilla::a11y::DocAccessible* aDocAccessible)
  {
    mDocAccessible = aDocAccessible;
  }
#endif

#ifdef MOZILLA_INTERNAL_API
  mozilla::StyleSetHandle StyleSet() const { return mStyleSet; }

  nsCSSFrameConstructor* FrameConstructor() const { return mFrameConstructor; }

  nsFrameManager* FrameManager() const {
    // reinterpret_cast is valid since nsFrameManager does not add
    // any members over nsFrameManagerBase.
    return reinterpret_cast<nsFrameManager*>
                           (const_cast<nsIPresShell*>(this)->mFrameManager);
  }

#endif

  /* Enable/disable author style level. Disabling author style disables the entire
   * author level of the cascade, including the HTML preshint level.
   */
  // XXX these could easily be inlined, but there is a circular #include
  // problem with nsStyleSet.
  void SetAuthorStyleDisabled(bool aDisabled);
  bool GetAuthorStyleDisabled() const;

  /*
   * Called when stylesheets are added/removed/enabled/disabled to
   * recompute style and clear other cached data as needed.  This will
   * not reconstruct style synchronously; if you need to do that, call
   * FlushPendingNotifications to flush out style reresolves.
   *
   * This handles the the addition and removal of the various types of
   * style rules that can be in CSS style sheets, such as @font-face
   * rules and @counter-style rules.
   *
   * It requires that StyleSheetAdded, StyleSheetRemoved,
   * StyleSheetApplicableStateChanged, StyleRuleAdded, StyleRuleRemoved,
   * or StyleRuleChanged has been called on the style sheets that have
   * changed.
   *
   * // XXXbz why do we have this on the interface anyway?  The only consumer
   * is calling AddOverrideStyleSheet/RemoveOverrideStyleSheet, and I think
   * those should just handle reconstructing style data...
   */
  void RestyleForCSSRuleChanges();

  /**
   * Update the style set somehow to take into account changed prefs which
   * affect document styling.
   */
  virtual void UpdatePreferenceStyles() = 0;

  /**
   * FrameSelection will return the Frame based selection API.
   * You cannot go back and forth anymore with QI between nsIDOM sel and
   * nsIFrame sel.
   */
  already_AddRefed<nsFrameSelection> FrameSelection();

  /**
   * ConstFrameSelection returns an object which methods are safe to use for
   * example in nsIFrame code.
   */
  const nsFrameSelection* ConstFrameSelection() const { return mSelection; }

  // Make shell be a document observer.  If called after Destroy() has
  // been called on the shell, this will be ignored.
  virtual void BeginObservingDocument() = 0;

  // Make shell stop being a document observer
  virtual void EndObservingDocument() = 0;

  /**
   * Return whether Initialize() was previously called.
   */
  bool DidInitialize() const { return mDidInitialize; }

  /**
   * Perform initialization. Constructs the frame for the root content
   * object and then enqueues a reflow of the frame model into the
   * specified width and height.
   *
   * The coordinates for aWidth and aHeight must be in standard nscoords.
   *
   * Callers of this method must hold a reference to this shell that
   * is guaranteed to survive through arbitrary script execution.
   * Calling Initialize can execute arbitrary script.
   */
  virtual nsresult Initialize(nscoord aWidth, nscoord aHeight) = 0;

  /**
   * Reflow the frame model into a new width and height.  The
   * coordinates for aWidth and aHeight must be in standard nscoord's.
   */
  virtual nsresult ResizeReflow(nscoord aWidth, nscoord aHeight, nscoord aOldWidth = 0, nscoord aOldHeight = 0) = 0;
  /**
   * Do the same thing as ResizeReflow but even if ResizeReflowOverride was
   * called previously.
   */
  virtual nsresult ResizeReflowIgnoreOverride(nscoord aWidth, nscoord aHeight, nscoord aOldWidth, nscoord aOldHeight) = 0;

  /**
   * Returns true if ResizeReflowOverride has been called.
   */
  virtual bool GetIsViewportOverridden() = 0;

  /**
   * Return true if the presshell expects layout flush.
   */
  virtual bool IsLayoutFlushObserver() = 0;

  /**
   * Called when document load completes.
   */
  virtual void LoadComplete() = 0;

  /**
   * This calls through to the frame manager to get the root frame.
   */
  virtual nsIFrame* GetRootFrameExternal() const;
  nsIFrame* GetRootFrame() const {
#ifdef MOZILLA_INTERNAL_API
    return mFrameManager->GetRootFrame();
#else
    return GetRootFrameExternal();
#endif
  }

  /*
   * Get root scroll frame from FrameManager()->GetRootFrame().
   */
  nsIFrame* GetRootScrollFrame() const;

  /*
   * The same as GetRootScrollFrame, but returns an nsIScrollableFrame
   */
  nsIScrollableFrame* GetRootScrollFrameAsScrollable() const;

  /*
   * The same as GetRootScrollFrame, but returns an nsIScrollableFrame.
   * Can be called by code not linked into gklayout.
   */
  virtual nsIScrollableFrame* GetRootScrollFrameAsScrollableExternal() const;

  /*
   * Gets nearest scrollable frame from current focused content or DOM
   * selection if there is no focused content. The frame is scrollable with
   * overflow:scroll or overflow:auto in some direction when aDirection is
   * eEither.  Otherwise, this returns a nearest frame that is scrollable in
   * the specified direction.
   */
  enum ScrollDirection { eHorizontal, eVertical, eEither };
  nsIScrollableFrame* GetFrameToScrollAsScrollable(ScrollDirection aDirection);

  /**
   * Returns the page sequence frame associated with the frame hierarchy.
   * Returns nullptr if not a paginated view.
   */
  virtual nsIPageSequenceFrame* GetPageSequenceFrame() const = 0;

  /**
  * Returns the canvas frame associated with the frame hierarchy.
  * Returns nullptr if is XUL document.
  */
  virtual nsCanvasFrame* GetCanvasFrame() const = 0;

  /**
   * Gets the placeholder frame associated with the specified frame. This is
   * a helper frame that forwards the request to the frame manager.
   */
  virtual nsIFrame* GetPlaceholderFrameFor(nsIFrame* aFrame) const = 0;

  /**
   * Tell the pres shell that a frame needs to be marked dirty and needs
   * Reflow.  It's OK if this is an ancestor of the frame needing reflow as
   * long as the ancestor chain between them doesn't cross a reflow root.
   *
   * The bit to add should be NS_FRAME_IS_DIRTY, NS_FRAME_HAS_DIRTY_CHILDREN
   * or nsFrameState(0); passing 0 means that dirty bits won't be set on the
   * frame or its ancestors/descendants, but that intrinsic widths will still
   * be marked dirty.  Passing aIntrinsicDirty = eResize and aBitToAdd = 0
   * would result in no work being done, so don't do that.
   */
  enum IntrinsicDirty {
    // XXXldb eResize should be renamed
    eResize,     // don't mark any intrinsic widths dirty
    eTreeChange, // mark intrinsic widths dirty on aFrame and its ancestors
    eStyleChange // Do eTreeChange, plus all of aFrame's descendants
  };
  enum ReflowRootHandling {
    ePositionOrSizeChange, // aFrame is changing position or size
    eNoPositionOrSizeChange, // ... NOT changing ...
    eInferFromBitToAdd // is changing iff (aBitToAdd == NS_FRAME_IS_DIRTY)

    // Note:  With eStyleChange, these can also apply to out-of-flows
    // in addition to aFrame.
  };
  virtual void FrameNeedsReflow(nsIFrame *aFrame,
                                IntrinsicDirty aIntrinsicDirty,
                                nsFrameState aBitToAdd,
                                ReflowRootHandling aRootHandling =
                                  eInferFromBitToAdd) = 0;

  /**
   * Calls FrameNeedsReflow on all fixed position children of the root frame.
   */
  virtual void MarkFixedFramesForReflow(IntrinsicDirty aIntrinsicDirty);

  /**
   * Tell the presshell that the given frame's reflow was interrupted.  This
   * will mark as having dirty children a path from the given frame (inclusive)
   * to the nearest ancestor with a dirty subtree, or to the reflow root
   * currently being reflowed if no such ancestor exists (inclusive).  This is
   * to be done immediately after reflow of the current reflow root completes.
   * This method must only be called during reflow, and the frame it's being
   * called on must be in the process of being reflowed when it's called.  This
   * method doesn't mark any intrinsic widths dirty and doesn't add any bits
   * other than NS_FRAME_HAS_DIRTY_CHILDREN.
   */
  virtual void FrameNeedsToContinueReflow(nsIFrame *aFrame) = 0;

  virtual void CancelAllPendingReflows() = 0;

  virtual void NotifyCounterStylesAreDirty() = 0;

  /**
   * Destroy the frames for aContent.  Note that this may destroy frames
   * for an ancestor instead - aDestroyedFramesFor contains the content node
   * where frames were actually destroyed (which should be used in the
   * CreateFramesFor call).  The frame tree state will be captured before
   * the frames are destroyed in the frame constructor.
   */
  virtual void DestroyFramesFor(nsIContent*  aContent,
                                nsIContent** aDestroyedFramesFor) = 0;
  /**
   * Create new frames for aContent.  It will use the last captured layout
   * history state captured in the frame constructor to restore the state
   * in the new frame tree.
   */
  virtual void CreateFramesFor(nsIContent* aContent) = 0;

  /**
   * Recreates the frames for a node
   */
  virtual nsresult RecreateFramesFor(nsIContent* aContent) = 0;

  void PostRecreateFramesFor(mozilla::dom::Element* aElement);
  void RestyleForAnimation(mozilla::dom::Element* aElement,
                           nsRestyleHint aHint);

  // ShadowRoot has APIs that can change styles so we only
  // want to restyle elements in the ShadowRoot and not the whole
  // document.
  virtual void RecordShadowStyleChange(mozilla::dom::ShadowRoot* aShadowRoot) = 0;

  /**
   * Determine if it is safe to flush all pending notifications
   * @param aIsSafeToFlush true if it is safe, false otherwise.
   *
   */
  virtual bool IsSafeToFlush() const = 0;

  /**
   * Flush pending notifications of the type specified.  This method
   * will not affect the content model; it'll just affect style and
   * frames. Callers that actually want up-to-date presentation (other
   * than the document itself) should probably be calling
   * nsIDocument::FlushPendingNotifications.
   *
   * @param aType the type of notifications to flush
   */
  virtual void FlushPendingNotifications(mozFlushType aType) = 0;
  virtual void FlushPendingNotifications(mozilla::ChangesToFlush aType) = 0;

  /**
   * Callbacks will be called even if reflow itself fails for
   * some reason.
   */
  virtual nsresult PostReflowCallback(nsIReflowCallback* aCallback) = 0;
  virtual void CancelReflowCallback(nsIReflowCallback* aCallback) = 0;

  virtual void ClearFrameRefs(nsIFrame* aFrame) = 0;

  /**
   * Get a reference rendering context. This is a context that should not
   * be rendered to, but is suitable for measuring text and performing
   * other non-rendering operations. Guaranteed to return non-null.
   */
  virtual already_AddRefed<gfxContext> CreateReferenceRenderingContext() = 0;

  /**
   * Informs the pres shell that the document is now at the anchor with
   * the given name.  If |aScroll| is true, scrolls the view of the
   * document so that the anchor with the specified name is displayed at
   * the top of the window.  If |aAnchorName| is empty, then this informs
   * the pres shell that there is no current target, and |aScroll| must
   * be false.  If |aAdditionalScrollFlags| is nsIPresShell::SCROLL_SMOOTH_AUTO
   * and |aScroll| is true, the scrolling may be performed with an animation.
   */
  virtual nsresult GoToAnchor(const nsAString& aAnchorName, bool aScroll,
                              uint32_t aAdditionalScrollFlags = 0) = 0;

  /**
   * Tells the presshell to scroll again to the last anchor scrolled to by
   * GoToAnchor, if any. This scroll only happens if the scroll
   * position has not changed since the last GoToAnchor. This is called
   * by nsDocumentViewer::LoadComplete. This clears the last anchor
   * scrolled to by GoToAnchor (we don't want to keep it alive if it's
   * removed from the DOM), so don't call this more than once.
   */
  virtual nsresult ScrollToAnchor() = 0;

  enum {
    SCROLL_TOP     = 0,
    SCROLL_BOTTOM  = 100,
    SCROLL_LEFT    = 0,
    SCROLL_RIGHT   = 100,
    SCROLL_CENTER  = 50,
    SCROLL_MINIMUM = -1
  };

  enum WhenToScroll {
    SCROLL_ALWAYS,
    SCROLL_IF_NOT_VISIBLE,
    SCROLL_IF_NOT_FULLY_VISIBLE
  };
  typedef struct ScrollAxis {
    int16_t mWhereToScroll;
    WhenToScroll mWhenToScroll : 8;
    bool mOnlyIfPerceivedScrollableDirection : 1;
  /**
   * @param aWhere: Either a percentage or a special value.
   *                nsIPresShell defines:
   *                * (Default) SCROLL_MINIMUM = -1: The visible area is
   *                scrolled to show the entire frame. If the frame is too
   *                large, the top and left edges are given precedence.
   *                * SCROLL_TOP = 0: The frame's upper edge is aligned with the
   *                top edge of the visible area.
   *                * SCROLL_BOTTOM = 100: The frame's bottom edge is aligned
   *                with the bottom edge of the visible area.
   *                * SCROLL_LEFT = 0: The frame's left edge is aligned with the
   *                left edge of the visible area.
   *                * SCROLL_RIGHT = 100: The frame's right edge is aligned with
   *                the right edge of the visible area.
   *                * SCROLL_CENTER = 50: The frame is centered along the axis
   *                the ScrollAxis is used for.
   *
   *                Other values are treated as a percentage, and the point
   *                "percent" down the frame is placed at the point "percent"
   *                down the visible area.
   * @param aWhen:
   *                * (Default) SCROLL_IF_NOT_FULLY_VISIBLE: Move the frame only
   *                if it is not fully visible (including if it's not visible
   *                at all). Note that in this case if the frame is too large to
   *                fit in view, it will only be scrolled if more of it can fit
   *                than is already in view.
   *                * SCROLL_IF_NOT_VISIBLE: Move the frame only if none of it
   *                is visible.
   *                * SCROLL_ALWAYS: Move the frame regardless of its current
   *                visibility.
   * @param aOnlyIfPerceivedScrollableDirection:
   *                If the direction is not a perceived scrollable direction (i.e.
   *                no scrollbar showing and less than one device pixel of
   *                scrollable distance), don't scroll. Defaults to false.
   */
    explicit ScrollAxis(int16_t aWhere = SCROLL_MINIMUM,
                        WhenToScroll aWhen = SCROLL_IF_NOT_FULLY_VISIBLE,
                        bool aOnlyIfPerceivedScrollableDirection = false) :
      mWhereToScroll(aWhere), mWhenToScroll(aWhen),
      mOnlyIfPerceivedScrollableDirection(aOnlyIfPerceivedScrollableDirection)
    {}
  } ScrollAxis;
  /**
   * Scrolls the view of the document so that the primary frame of the content
   * is displayed in the window. Layout is flushed before scrolling.
   *
   * @param aContent  The content object of which primary frame should be
   *                  scrolled into view.
   * @param aVertical How to align the frame vertically and when to do so.
   *                  This is a ScrollAxis of Where and When.
   * @param aHorizontal How to align the frame horizontally and when to do so.
   *                  This is a ScrollAxis of Where and When.
   * @param aFlags    If SCROLL_FIRST_ANCESTOR_ONLY is set, only the nearest
   *                  scrollable ancestor is scrolled, otherwise all
   *                  scrollable ancestors may be scrolled if necessary.
   *                  If SCROLL_OVERFLOW_HIDDEN is set then we may scroll in a
   *                  direction even if overflow:hidden is specified in that
   *                  direction; otherwise we will not scroll in that direction
   *                  when overflow:hidden is set for that direction.
   *                  If SCROLL_NO_PARENT_FRAMES is set then we only scroll
   *                  nodes in this document, not in any parent documents which
   *                  contain this document in a iframe or the like.
   *                  If SCROLL_SMOOTH is set and CSSOM-VIEW scroll-behavior
   *                  is enabled, we will scroll smoothly using
   *                  nsIScrollableFrame::ScrollMode::SMOOTH_MSD; otherwise,
   *                  nsIScrollableFrame::ScrollMode::INSTANT will be used.
   *                  If SCROLL_SMOOTH_AUTO is set, the CSSOM-View
   *                  scroll-behavior attribute is set to 'smooth' on the
   *                  scroll frame, and CSSOM-VIEW scroll-behavior is enabled,
   *                  we will scroll smoothly using
   *                  nsIScrollableFrame::ScrollMode::SMOOTH_MSD; otherwise,
   *                  nsIScrollableFrame::ScrollMode::INSTANT will be used.
   */
  virtual nsresult ScrollContentIntoView(nsIContent* aContent,
                                                     ScrollAxis  aVertical,
                                                     ScrollAxis  aHorizontal,
                                                     uint32_t    aFlags) = 0;

  enum {
    SCROLL_FIRST_ANCESTOR_ONLY = 0x01,
    SCROLL_OVERFLOW_HIDDEN = 0x02,
    SCROLL_NO_PARENT_FRAMES = 0x04,
    SCROLL_SMOOTH = 0x08,
    SCROLL_SMOOTH_AUTO = 0x10
  };
  /**
   * Scrolls the view of the document so that the given area of a frame
   * is visible, if possible. Layout is not flushed before scrolling.
   *
   * @param aRect relative to aFrame
   * @param aVertical see ScrollContentIntoView and ScrollAxis
   * @param aHorizontal see ScrollContentIntoView and ScrollAxis
   * @param aFlags if SCROLL_FIRST_ANCESTOR_ONLY is set, only the
   * nearest scrollable ancestor is scrolled, otherwise all
   * scrollable ancestors may be scrolled if necessary
   * if SCROLL_OVERFLOW_HIDDEN is set then we may scroll in a direction
   * even if overflow:hidden is specified in that direction; otherwise
   * we will not scroll in that direction when overflow:hidden is
   * set for that direction
   * If SCROLL_NO_PARENT_FRAMES is set then we only scroll
   * nodes in this document, not in any parent documents which
   * contain this document in a iframe or the like.
   * @return true if any scrolling happened, false if no scrolling happened
   */
  virtual bool ScrollFrameRectIntoView(nsIFrame*     aFrame,
                                       const nsRect& aRect,
                                       ScrollAxis    aVertical,
                                       ScrollAxis    aHorizontal,
                                       uint32_t      aFlags) = 0;

  /**
   * Determine if a rectangle specified in the frame's coordinate system
   * intersects the viewport "enough" to be considered visible.
   * @param aFrame frame that aRect coordinates are specified relative to
   * @param aRect rectangle in twips to test for visibility
   * @param aMinTwips is the minimum distance in from the edge of the viewport
   *                  that an object must be to be counted visible
   * @return nsRectVisibility_kVisible if the rect is visible
   *         nsRectVisibility_kAboveViewport
   *         nsRectVisibility_kBelowViewport
   *         nsRectVisibility_kLeftOfViewport
   *         nsRectVisibility_kRightOfViewport rectangle is outside the viewport
   *         in the specified direction
   */
  virtual nsRectVisibility GetRectVisibility(nsIFrame *aFrame,
                                             const nsRect &aRect,
                                             nscoord aMinTwips) const = 0;

  /**
   * Suppress notification of the frame manager that frames are
   * being destroyed.
   */
  virtual void SetIgnoreFrameDestruction(bool aIgnore) = 0;

  /**
   * Notification sent by a frame informing the pres shell that it is about to
   * be destroyed.
   * This allows any outstanding references to the frame to be cleaned up
   */
  virtual void NotifyDestroyingFrame(nsIFrame* aFrame) = 0;

  /**
   * Get the AccessibleCaretEventHub, if it exists. AddRefs it.
   */
  virtual already_AddRefed<mozilla::AccessibleCaretEventHub> GetAccessibleCaretEventHub() const = 0;

  /**
   * Get the caret, if it exists. AddRefs it.
   */
  virtual already_AddRefed<nsCaret> GetCaret() const = 0;

  /**
   * Set the current caret to a new caret. To undo this, call RestoreCaret.
   */
  virtual void SetCaret(nsCaret *aNewCaret) = 0;

  /**
   * Restore the caret to the original caret that this pres shell was created
   * with.
   */
  virtual void RestoreCaret() = 0;

  /**
   * Should the images have borders etc.  Actual visual effects are determined
   * by the frames.  Visual effects may not effect layout, only display.
   * Takes effect on next repaint, does not force a repaint itself.
   *
   * @param aInEnable  if true, visual selection effects are enabled
   *                   if false visual selection effects are disabled
   */
  NS_IMETHOD SetSelectionFlags(int16_t aInEnable) = 0;

  /**
    * Gets the current state of non text selection effects
    * @return   current state of non text selection,
    *           as set by SetDisplayNonTextSelection
    */
  int16_t GetSelectionFlags() const { return mSelectionFlags; }

  virtual mozilla::dom::Selection*
    GetCurrentSelection(mozilla::SelectionType aSelectionType) = 0;

  /**
   * Gets a selection controller for the focused content in the DOM window
   * for mDocument.
   *
   * @param aFocusedContent     If there is focused content in the DOM window,
   *                            the focused content will be returned.  This may
   *                            be nullptr if it's not necessary.
   * @return                    A selection controller for focused content.
   *                            E.g., if an <input> element has focus, returns
   *                            the independent selection controller of it.
   *                            If the DOM window does not have focused content
   *                            (similar to Document.activeElement), returns
   *                            nullptr.
   */
  virtual already_AddRefed<nsISelectionController>
            GetSelectionControllerForFocusedContent(
              nsIContent** aFocusedContent = nullptr) = 0;

  /**
    * Interface to dispatch events via the presshell
    * @note The caller must have a strong reference to the PresShell.
    */
  virtual nsresult HandleEventWithTarget(
                                 mozilla::WidgetEvent* aEvent,
                                 nsIFrame* aFrame,
                                 nsIContent* aContent,
                                 nsEventStatus* aStatus) = 0;

  /**
   * Dispatch event to content only (NOT full processing)
   * @note The caller must have a strong reference to the PresShell.
   */
  virtual nsresult HandleDOMEventWithTarget(
                                 nsIContent* aTargetContent,
                                 mozilla::WidgetEvent* aEvent,
                                 nsEventStatus* aStatus) = 0;

  /**
   * Dispatch event to content only (NOT full processing)
   * @note The caller must have a strong reference to the PresShell.
   */
  virtual nsresult HandleDOMEventWithTarget(nsIContent* aTargetContent,
                                                        nsIDOMEvent* aEvent,
                                                        nsEventStatus* aStatus) = 0;

  /**
   * Dispatch AfterKeyboardEvent with specific target.
   */
  virtual void DispatchAfterKeyboardEvent(nsINode* aTarget,
                                          const mozilla::WidgetKeyboardEvent& aEvent,
                                          bool aEmbeddedCancelled) = 0;

  /**
   * Return whether or not the event is valid to be dispatched
   */
  virtual bool CanDispatchEvent(
      const mozilla::WidgetGUIEvent* aEvent = nullptr) const = 0;

  /**
    * Gets the current target event frame from the PresShell
    */
  virtual nsIFrame* GetEventTargetFrame() = 0;

  /**
    * Gets the current target event frame from the PresShell
    */
  virtual already_AddRefed<nsIContent> GetEventTargetContent(
                                                     mozilla::WidgetEvent* aEvent) = 0;

  /**
   * Get and set the history state for the current document
   */

  virtual nsresult CaptureHistoryState(nsILayoutHistoryState** aLayoutHistoryState) = 0;

  /**
   * Determine if reflow is currently locked
   * returns true if reflow is locked, false otherwise
   */
  bool IsReflowLocked() const { return mIsReflowing; }

  /**
   * Called to find out if painting is suppressed for this presshell.  If it is suppressd,
   * we don't allow the painting of any layer but the background, and we don't
   * recur into our children.
   */
  bool IsPaintingSuppressed() const { return mPaintingSuppressed; }

  /**
   * Pause painting by freezing the refresh driver of this and all parent
   * presentations. This may not have the desired effect if this pres shell
   * has its own refresh driver.
   */
  virtual void PausePainting() = 0;

  /**
   * Resume painting by thawing the refresh driver of this and all parent
   * presentations. This may not have the desired effect if this pres shell
   * has its own refresh driver.
   */
  virtual void ResumePainting() = 0;

  /**
   * Unsuppress painting.
   */
  virtual void UnsuppressPainting() = 0;

  /**
   * Called to disable nsITheme support in a specific presshell.
   */
  void DisableThemeSupport()
  {
    // Doesn't have to be dynamic.  Just set the bool.
    mIsThemeSupportDisabled = true;
  }

  /**
   * Indicates whether theme support is enabled.
   */
  bool IsThemeSupportEnabled() const { return !mIsThemeSupportDisabled; }

  /**
   * Get the set of agent style sheets for this presentation
   */
  virtual nsresult GetAgentStyleSheets(
      nsTArray<RefPtr<mozilla::StyleSheet>>& aSheets) = 0;

  /**
   * Replace the set of agent style sheets
   */
  virtual nsresult SetAgentStyleSheets(
      const nsTArray<RefPtr<mozilla::StyleSheet>>& aSheets) = 0;

  /**
   * Add an override style sheet for this presentation
   */
  virtual nsresult AddOverrideStyleSheet(mozilla::StyleSheet* aSheet) = 0;

  /**
   * Remove an override style sheet
   */
  virtual nsresult RemoveOverrideStyleSheet(mozilla::StyleSheet* aSheet) = 0;

  /**
   * Reconstruct frames for all elements in the document
   */
  virtual nsresult ReconstructFrames() = 0;

  /**
   * Notify that a content node's state has changed
   */
  virtual void ContentStateChanged(nsIDocument* aDocument,
                                   nsIContent* aContent,
                                   mozilla::EventStates aStateMask) = 0;

  /**
   * See if reflow verification is enabled. To enable reflow verification add
   * "verifyreflow:1" to your MOZ_LOG environment variable (any non-zero
   * debug level will work). Or, call SetVerifyReflowEnable with true.
   */
  static bool GetVerifyReflowEnable();

  /**
   * Set the verify-reflow enable flag.
   */
  static void SetVerifyReflowEnable(bool aEnabled);

  virtual nsIFrame* GetAbsoluteContainingBlock(nsIFrame* aFrame);

#ifdef MOZ_REFLOW_PERF
  virtual void DumpReflows() = 0;
  virtual void CountReflows(const char * aName, nsIFrame * aFrame) = 0;
  virtual void PaintCount(const char * aName,
                                      nsRenderingContext* aRenderingContext,
                                      nsPresContext * aPresContext,
                                      nsIFrame * aFrame,
                                      const nsPoint& aOffset,
                                      uint32_t aColor) = 0;
  virtual void SetPaintFrameCount(bool aOn) = 0;
  virtual bool IsPaintingFrameCounts() = 0;
#endif

#ifdef DEBUG
  // Debugging hooks
  virtual void ListStyleContexts(nsIFrame *aRootFrame, FILE *out,
                                 int32_t aIndent = 0) = 0;

  virtual void ListStyleSheets(FILE *out, int32_t aIndent = 0) = 0;
  virtual void VerifyStyleTree() = 0;
#endif

#ifdef ACCESSIBILITY
  /**
   * Return true if accessibility is active.
   */
  static bool IsAccessibilityActive();

  /**
   * Return accessibility service if accessibility is active.
   */
  static nsAccessibilityService* AccService();
#endif

  /**
   * Stop all active elements (plugins and the caret) in this presentation and
   * in the presentations of subdocuments.  Resets painting to a suppressed state.
   * XXX this should include image animations
   */
  virtual void Freeze() = 0;
  bool IsFrozen() { return mFrozen; }

  /**
   * Restarts active elements (plugins) in this presentation and in the
   * presentations of subdocuments, then do a full invalidate of the content area.
   */
  virtual void Thaw() = 0;

  virtual void FireOrClearDelayedEvents(bool aFireEvents) = 0;

  /**
   * When this shell is disconnected from its containing docshell, we
   * lose our container pointer.  However, we'd still like to be able to target
   * user events at the docshell's parent.  This pointer allows us to do that.
   * It should not be used for any other purpose.
   */
  void SetForwardingContainer(const mozilla::WeakPtr<nsDocShell> &aContainer);

  /**
   * Render the document into an arbitrary gfxContext
   * Designed for getting a picture of a document or a piece of a document
   * Note that callers will generally want to call FlushPendingNotifications
   * to get an up-to-date view of the document
   * @param aRect is the region to capture into the offscreen buffer, in the
   * root frame's coordinate system (if aIgnoreViewportScrolling is false)
   * or in the root scrolled frame's coordinate system
   * (if aIgnoreViewportScrolling is true). The coordinates are in appunits.
   * @param aFlags see below;
   *   set RENDER_IS_UNTRUSTED if the contents may be passed to malicious
   * agents. E.g. we might choose not to paint the contents of sensitive widgets
   * such as the file name in a file upload widget, and we might choose not
   * to paint themes.
   *   set RENDER_IGNORE_VIEWPORT_SCROLLING to ignore
   * clipping and scrollbar painting due to scrolling in the viewport
   *   set RENDER_CARET to draw the caret if one would be visible
   * (by default the caret is never drawn)
   *   set RENDER_USE_LAYER_MANAGER to force rendering to go through
   * the layer manager for the window. This may be unexpectedly slow
   * (if the layer manager must read back data from the GPU) or low-quality
   * (if the layer manager reads back pixel data and scales it
   * instead of rendering using the appropriate scaling). It may also
   * slow everything down if the area rendered does not correspond to the
   * normal visible area of the window.
   *   set RENDER_ASYNC_DECODE_IMAGES to avoid having images synchronously
   * decoded during rendering.
   * (by default images decode synchronously with RenderDocument)
   *   set RENDER_DOCUMENT_RELATIVE to render the document as if there has been
   * no scrolling and interpret |aRect| relative to the document instead of the
   * CSS viewport. Only considered if RENDER_IGNORE_VIEWPORT_SCROLLING is set
   * or the document is in ignore viewport scrolling mode
   * (nsIPresShell::SetIgnoreViewportScrolling/IgnoringViewportScrolling).
   * @param aBackgroundColor a background color to render onto
   * @param aRenderedContext the gfxContext to render to. We render so that
   * one CSS pixel in the source document is rendered to one unit in the current
   * transform.
   */
  enum {
    RENDER_IS_UNTRUSTED = 0x01,
    RENDER_IGNORE_VIEWPORT_SCROLLING = 0x02,
    RENDER_CARET = 0x04,
    RENDER_USE_WIDGET_LAYERS = 0x08,
    RENDER_ASYNC_DECODE_IMAGES = 0x10,
    RENDER_DOCUMENT_RELATIVE = 0x20,
    RENDER_DRAWWINDOW_NOT_FLUSHING = 0x40
  };
  virtual nsresult RenderDocument(const nsRect& aRect, uint32_t aFlags,
                                  nscolor aBackgroundColor,
                                  gfxContext* aRenderedContext) = 0;

  enum {
    RENDER_IS_IMAGE = 0x100,
    RENDER_AUTO_SCALE = 0x80
  };

  /**
   * Renders a node aNode to a surface and returns it. The aRegion may be used
   * to clip the rendering. This region is measured in CSS pixels from the
   * edge of the presshell area. The aPoint, aScreenRect and aFlags arguments
   * function in a similar manner as RenderSelection.
   */
  virtual already_AddRefed<mozilla::gfx::SourceSurface>
  RenderNode(nsIDOMNode* aNode,
             nsIntRegion* aRegion,
             const mozilla::LayoutDeviceIntPoint aPoint,
             mozilla::LayoutDeviceIntRect* aScreenRect,
             uint32_t aFlags) = 0;

  /**
   * Renders a selection to a surface and returns it. This method is primarily
   * intended to create the drag feedback when dragging a selection.
   *
   * aScreenRect will be filled in with the bounding rectangle of the
   * selection area on screen.
   *
   * If the area of the selection is large and the RENDER_AUTO_SCALE flag is
   * set, the image will be scaled down. The argument aPoint is used in this
   * case as a reference point when determining the new screen rectangle after
   * scaling. Typically, this will be the mouse position, so that the screen
   * rectangle is positioned such that the mouse is over the same point in the
   * scaled image as in the original. When scaling does not occur, the mouse
   * point isn't used because the position can be determined from the displayed
   * frames.
   */
  virtual already_AddRefed<mozilla::gfx::SourceSurface>
  RenderSelection(nsISelection* aSelection,
                  const mozilla::LayoutDeviceIntPoint aPoint,
                  mozilla::LayoutDeviceIntRect* aScreenRect,
                  uint32_t aFlags) = 0;

  void AddWeakFrameInternal(nsWeakFrame* aWeakFrame);
  virtual void AddWeakFrameExternal(nsWeakFrame* aWeakFrame);

  void AddWeakFrame(nsWeakFrame* aWeakFrame)
  {
#ifdef MOZILLA_INTERNAL_API
    AddWeakFrameInternal(aWeakFrame);
#else
    AddWeakFrameExternal(aWeakFrame);
#endif
  }

  void RemoveWeakFrameInternal(nsWeakFrame* aWeakFrame);
  virtual void RemoveWeakFrameExternal(nsWeakFrame* aWeakFrame);

  void RemoveWeakFrame(nsWeakFrame* aWeakFrame)
  {
#ifdef MOZILLA_INTERNAL_API
    RemoveWeakFrameInternal(aWeakFrame);
#else
    RemoveWeakFrameExternal(aWeakFrame);
#endif
  }

#ifdef DEBUG
  nsIFrame* GetDrawEventTargetFrame() { return mDrawEventTargetFrame; }
#endif

  /**
   * Stop or restart non synthetic test mouse event handling on *all*
   * presShells.
   *
   * @param aDisable If true, disable all non synthetic test mouse
   * events on all presShells.  Otherwise, enable them.
   */
  virtual void DisableNonTestMouseEvents(bool aDisable) = 0;

  /**
   * Record the background color of the most recently drawn canvas. This color
   * is composited on top of the user's default background color and then used
   * to draw the background color of the canvas. See PresShell::Paint,
   * PresShell::PaintDefaultBackground, and nsDocShell::SetupNewViewer;
   * bug 488242, bug 476557 and other bugs mentioned there.
   */
  void SetCanvasBackground(nscolor aColor) { mCanvasBackgroundColor = aColor; }
  nscolor GetCanvasBackground() { return mCanvasBackgroundColor; }

  /**
   * Use the current frame tree (if it exists) to update the background
   * color of the most recently drawn canvas.
   */
  virtual void UpdateCanvasBackground() = 0;

  /**
   * Add a solid color item to the bottom of aList with frame aFrame and bounds
   * aBounds. Checks first if this needs to be done by checking if aFrame is a
   * canvas frame (if the FORCE_DRAW flag is passed then this check is skipped).
   * aBackstopColor is composed behind the background color of the canvas, it is
   * transparent by default.
   */
  enum {
    FORCE_DRAW = 0x01
  };
  virtual void AddCanvasBackgroundColorItem(nsDisplayListBuilder& aBuilder,
                                            nsDisplayList& aList,
                                            nsIFrame* aFrame,
                                            const nsRect& aBounds,
                                            nscolor aBackstopColor = NS_RGBA(0,0,0,0),
                                            uint32_t aFlags = 0) = 0;


  /**
   * Add a solid color item to the bottom of aList with frame aFrame and
   * bounds aBounds representing the dark grey background behind the page of a
   * print preview presentation.
   */
  virtual void AddPrintPreviewBackgroundItem(nsDisplayListBuilder& aBuilder,
                                             nsDisplayList& aList,
                                             nsIFrame* aFrame,
                                             const nsRect& aBounds) = 0;

  /**
   * Computes the backstop color for the view: transparent if in a transparent
   * widget, otherwise the PresContext default background color. This color is
   * only visible if the contents of the view as a whole are translucent.
   */
  virtual nscolor ComputeBackstopColor(nsView* aDisplayRoot) = 0;

  void ObserveNativeAnonMutationsForPrint(bool aObserve)
  {
    mObservesMutationsForPrint = aObserve;
  }
  bool ObservesNativeAnonMutationsForPrint()
  {
    return mObservesMutationsForPrint;
  }

  virtual nsresult SetIsActive(bool aIsActive) = 0;

  bool IsActive()
  {
    return mIsActive;
  }

  // mouse capturing
  static CapturingContentInfo gCaptureInfo;

  class PointerCaptureInfo final
  {
  public:
    nsCOMPtr<nsIContent> mPendingContent;
    nsCOMPtr<nsIContent> mOverrideContent;

    explicit PointerCaptureInfo(nsIContent* aPendingContent)
      : mPendingContent(aPendingContent)
    {
      MOZ_COUNT_CTOR(PointerCaptureInfo);
    }

    ~PointerCaptureInfo()
    {
      MOZ_COUNT_DTOR(PointerCaptureInfo);
    }

    bool Empty()
    {
      return !(mPendingContent || mOverrideContent);
    }
  };

  class PointerInfo final
  {
  public:
    uint16_t mPointerType;
    bool mActiveState;
    bool mPrimaryState;
    explicit PointerInfo(bool aActiveState, uint16_t aPointerType,
                         bool aPrimaryState)
      : mPointerType(aPointerType)
      , mActiveState(aActiveState)
      , mPrimaryState(aPrimaryState)
    {
    }
  };

  static void DispatchGotOrLostPointerCaptureEvent(
                bool aIsGotCapture,
                const mozilla::WidgetPointerEvent* aPointerEvent,
                nsIContent* aCaptureTarget);

  static PointerCaptureInfo* GetPointerCaptureInfo(uint32_t aPointerId);
  static void SetPointerCapturingContent(uint32_t aPointerId,
                                         nsIContent* aContent);
  static void ReleasePointerCapturingContent(uint32_t aPointerId);
  static nsIContent* GetPointerCapturingContent(uint32_t aPointerId);

  // CheckPointerCaptureState checks cases, when got/lostpointercapture events
  // should be fired.
  static void CheckPointerCaptureState(
                const mozilla::WidgetPointerEvent* aPointerEvent);

  // GetPointerInfo returns true if pointer with aPointerId is situated in
  // device, false otherwise.
  // aActiveState is additional information, which shows state of pointer like
  // button state for mouse.
  static bool GetPointerInfo(uint32_t aPointerId, bool& aActiveState);

  // GetPointerType returns pointer type like mouse, pen or touch for pointer
  // event with pointerId
  static uint16_t GetPointerType(uint32_t aPointerId);

  // GetPointerPrimaryState returns state of attribute isPrimary for pointer
  // event with pointerId
  static bool GetPointerPrimaryState(uint32_t aPointerId);

  /**
   * When capturing content is set, it traps all mouse events and retargets
   * them at this content node. If capturing is not allowed
   * (gCaptureInfo.mAllowed is false), then capturing is not set. However, if
   * the CAPTURE_IGNOREALLOWED flag is set, the allowed state is ignored and
   * capturing is set regardless. To disable capture, pass null for the value
   * of aContent.
   *
   * If CAPTURE_RETARGETTOELEMENT is set, all mouse events are targeted at
   * aContent only. Otherwise, mouse events are targeted at aContent or its
   * descendants. That is, descendants of aContent receive mouse events as
   * they normally would, but mouse events outside of aContent are retargeted
   * to aContent.
   *
   * If CAPTURE_PREVENTDRAG is set then drags are prevented from starting while
   * this capture is active.
   *
   * If CAPTURE_POINTERLOCK is set, similar to CAPTURE_RETARGETTOELEMENT, then
   * events are targeted at aContent, but capturing is held more strongly (i.e.,
   * calls to SetCapturingContent won't unlock unless CAPTURE_POINTERLOCK is
   * set again).
   */
  static void SetCapturingContent(nsIContent* aContent, uint8_t aFlags);

  /**
   * Return the active content currently capturing the mouse if any.
   */
  static nsIContent* GetCapturingContent()
  {
    return gCaptureInfo.mContent;
  }

  /**
   * Allow or disallow mouse capturing.
   */
  static void AllowMouseCapture(bool aAllowed)
  {
    gCaptureInfo.mAllowed = aAllowed;
  }

  /**
   * Returns true if there is an active mouse capture that wants to prevent
   * drags.
   */
  static bool IsMouseCapturePreventingDrag()
  {
    return gCaptureInfo.mPreventDrag && gCaptureInfo.mContent;
  }

  /**
   * Keep track of how many times this presshell has been rendered to
   * a window.
   */
  uint64_t GetPaintCount() { return mPaintCount; }
  void IncrementPaintCount() { ++mPaintCount; }

  /**
   * Get the root DOM window of this presShell.
   */
  virtual already_AddRefed<nsPIDOMWindowOuter> GetRootWindow() = 0;

  /**
   * Get the layer manager for the widget of the root view, if it has
   * one.
   */
  virtual LayerManager* GetLayerManager() = 0;

  /**
   * Return true iff there is a widget rendering this presShell and that
   * widget is APZ-enabled.
   */
  virtual bool AsyncPanZoomEnabled() = 0;

  /**
   * Track whether we're ignoring viewport scrolling for the purposes
   * of painting.  If we are ignoring, then layers aren't clipped to
   * the CSS viewport and scrollbars aren't drawn.
   */
  virtual void SetIgnoreViewportScrolling(bool aIgnore) = 0;
  bool IgnoringViewportScrolling() const
  { return mRenderFlags & STATE_IGNORING_VIEWPORT_SCROLLING; }

   /**
   * Set a "resolution" for the document, which if not 1.0 will
   * allocate more or fewer pixels for rescalable content by a factor
   * of |resolution| in both dimensions.  Return NS_OK iff the
   * resolution bounds are sane, and the resolution of this was
   * actually updated.
   *
   * The resolution defaults to 1.0.
   */
  virtual nsresult SetResolution(float aResolution) = 0;
  float GetResolution() const { return mResolution.valueOr(1.0); }
  virtual float GetCumulativeResolution() = 0;

  /**
   * Calculate the cumulative scale resolution from this document up to
   * but not including the root document.
   */
  virtual float GetCumulativeNonRootScaleResolution() = 0;

  /**
   * Was the current resolution set by the user or just default initialized?
   */
  bool IsResolutionSet() { return mResolution.isSome(); }

  /**
   * Similar to SetResolution() but also increases the scale of the content
   * by the same amount.
   */
  virtual nsresult SetResolutionAndScaleTo(float aResolution) = 0;

  /**
   * Return whether we are scaling to the set resolution.
   * This is initially false; it's set to true by a call to
   * SetResolutionAndScaleTo(), and set to false by a call to SetResolution().
   */
  virtual bool ScaleToResolution() const = 0;

  /**
   * Used by session restore code to restore a resolution before the first
   * paint.
   */
  virtual void SetRestoreResolution(float aResolution,
                                    mozilla::LayoutDeviceIntSize aDisplaySize) = 0;

  /**
   * Returns whether we are in a DrawWindow() call that used the
   * DRAWWINDOW_DO_NOT_FLUSH flag.
   */
  bool InDrawWindowNotFlushing() const
  { return mRenderFlags & STATE_DRAWWINDOW_NOT_FLUSHING; }

  /**
   * Set the isFirstPaint flag.
   */
  void SetIsFirstPaint(bool aIsFirstPaint) { mIsFirstPaint = aIsFirstPaint; }

  /**
   * Get the isFirstPaint flag.
   */
  bool GetIsFirstPaint() const { return mIsFirstPaint; }

  uint32_t GetPresShellId() { return mPresShellId; }

  /**
   * Dispatch a mouse move event based on the most recent mouse position if
   * this PresShell is visible. This is used when the contents of the page
   * moved (aFromScroll is false) or scrolled (aFromScroll is true).
   */
  virtual void SynthesizeMouseMove(bool aFromScroll) = 0;

  enum PaintFlags {
    /* Update the layer tree and paint PaintedLayers. If this is not specified,
     * we may still have to do it if the layer tree lost PaintedLayer contents
     * we need for compositing. */
    PAINT_LAYERS = 0x01,
    /* Composite layers to the window. */
    PAINT_COMPOSITE = 0x02,
    /* Sync-decode images. */
    PAINT_SYNC_DECODE_IMAGES = 0x04
  };
  virtual void Paint(nsView* aViewToPaint, const nsRegion& aDirtyRegion,
                     uint32_t aFlags) = 0;
  virtual nsresult HandleEvent(nsIFrame* aFrame,
                               mozilla::WidgetGUIEvent* aEvent,
                               bool aDontRetargetEvents,
                               nsEventStatus* aEventStatus,
                               nsIContent** aTargetContent = nullptr) = 0;
  virtual bool ShouldIgnoreInvalidation() = 0;
  /**
   * Notify that we're going to call Paint with PAINT_LAYERS
   * on the pres shell for a widget (which might not be this one, since
   * WillPaint is called on all presshells in the same toplevel window as the
   * painted widget). This is issued at a time when it's safe to modify
   * widget geometry.
   */
  virtual void WillPaint() = 0;
  /**
   * Notify that we're going to call Paint with PAINT_COMPOSITE.
   * Fires on the presshell for the painted widget.
   * This is issued at a time when it's safe to modify widget geometry.
   */
  virtual void WillPaintWindow() = 0;
  /**
   * Notify that we called Paint with PAINT_COMPOSITE.
   * Fires on the presshell for the painted widget.
   * This is issued at a time when it's safe to modify widget geometry.
   */
  virtual void DidPaintWindow() = 0;

  /**
   * Ensures that the refresh driver is running, and schedules a view
   * manager flush on the next tick.
   *
   * @param aType PAINT_DELAYED_COMPRESS : Schedule a paint to be executed after a delay, and
   * put FrameLayerBuilder in 'compressed' mode that avoids short cut optimizations.
   */
  enum PaintType {
    PAINT_DEFAULT,
    PAINT_DELAYED_COMPRESS
  };
  virtual void ScheduleViewManagerFlush(PaintType aType = PAINT_DEFAULT) = 0;
  virtual void ClearMouseCaptureOnView(nsView* aView) = 0;
  virtual bool IsVisible() = 0;
  virtual void DispatchSynthMouseMove(mozilla::WidgetGUIEvent* aEvent,
                                      bool aFlushOnHoverChange) = 0;

  virtual void AddSizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf,
                                      nsArenaMemoryStats *aArenaObjectsSize,
                                      size_t *aPresShellSize,
                                      size_t *aStyleSetsSize,
                                      size_t *aTextRunsSize,
                                      size_t *aPresContextSize) = 0;

  /**
   * Methods that retrieve the cached font inflation preferences.
   */
  uint32_t FontSizeInflationEmPerLine() const {
    return mFontSizeInflationEmPerLine;
  }

  uint32_t FontSizeInflationMinTwips() const {
    return mFontSizeInflationMinTwips;
  }

  uint32_t FontSizeInflationLineThreshold() const {
    return mFontSizeInflationLineThreshold;
  }

  bool FontSizeInflationForceEnabled() const {
    return mFontSizeInflationForceEnabled;
  }

  bool FontSizeInflationDisabledInMasterProcess() const {
    return mFontSizeInflationDisabledInMasterProcess;
  }

  /**
   * Determine if font size inflation is enabled. This value is cached until
   * it becomes dirty.
   *
   * @returns true, if font size inflation is enabled; false otherwise.
   */
  bool FontSizeInflationEnabled();

  /**
   * Notify the pres shell that an event occurred making the current value of
   * mFontSizeInflationEnabled invalid. This will schedule a recomputation of
   * whether font size inflation is enabled on the next call to
   * FontSizeInflationEnabled().
   */
  void NotifyFontSizeInflationEnabledIsDirty()
  {
    mFontSizeInflationEnabledIsDirty = true;
  }

  virtual void AddInvalidateHiddenPresShellObserver(nsRefreshDriver *aDriver) = 0;

  void InvalidatePresShellIfHidden();
  void CancelInvalidatePresShellIfHidden();


  //////////////////////////////////////////////////////////////////////////////
  // Approximate frame visibility tracking public API.
  //////////////////////////////////////////////////////////////////////////////

  /// Schedule an update of the list of approximately visible frames "soon".
  /// This lets the refresh driver know that we want a visibility update in the
  /// near future. The refresh driver applies its own heuristics and throttling
  /// to decide when to actually perform the visibility update.
  virtual void ScheduleApproximateFrameVisibilityUpdateSoon() = 0;

  /// Schedule an update of the list of approximately visible frames "now". The
  /// update runs asynchronously, but it will be posted to the event loop
  /// immediately. Prefer the "soon" variation of this method when possible, as
  /// this variation ignores the refresh driver's heuristics.
  virtual void ScheduleApproximateFrameVisibilityUpdateNow() = 0;

  /// Clears the current list of approximately visible frames on this pres shell
  /// and replaces it with frames that are in the display list @aList.
  virtual void RebuildApproximateFrameVisibilityDisplayList(const nsDisplayList& aList) = 0;
  virtual void RebuildApproximateFrameVisibility(nsRect* aRect = nullptr,
                                                 bool aRemoveOnly = false) = 0;

  /// Ensures @aFrame is in the list of approximately visible frames.
  virtual void EnsureFrameInApproximatelyVisibleList(nsIFrame* aFrame) = 0;

  /// Removes @aFrame from the list of approximately visible frames if present.
  virtual void RemoveFrameFromApproximatelyVisibleList(nsIFrame* aFrame) = 0;

  /// Whether we should assume all frames are visible.
  virtual bool AssumeAllFramesVisible() = 0;


  /**
   * Returns whether the document's style set's rule processor for the
   * specified level of the cascade is shared by multiple style sets.
   *
   * @param aSheetType One of the nsIStyleSheetService.*_SHEET constants.
   */
  nsresult HasRuleProcessorUsedByMultipleStyleSets(uint32_t aSheetType,
                                                   bool* aRetVal);

  /**
   * Refresh observer management.
   */
protected:
  virtual bool AddRefreshObserverExternal(nsARefreshObserver* aObserver,
                                          mozFlushType aFlushType);
  bool AddRefreshObserverInternal(nsARefreshObserver* aObserver,
                                  mozFlushType aFlushType);
  virtual bool RemoveRefreshObserverExternal(nsARefreshObserver* aObserver,
                                             mozFlushType aFlushType);
  bool RemoveRefreshObserverInternal(nsARefreshObserver* aObserver,
                                     mozFlushType aFlushType);

  /**
   * Do computations necessary to determine if font size inflation is enabled.
   * This value is cached after computation, as the computation is somewhat
   * expensive.
   */
  void RecomputeFontSizeInflationEnabled();

  void RecordAlloc(void* aPtr) {
#ifdef DEBUG
    MOZ_ASSERT(!mAllocatedPointers.Contains(aPtr));
    mAllocatedPointers.PutEntry(aPtr);
#endif
  }

  void RecordFree(void* aPtr) {
#ifdef DEBUG
    MOZ_ASSERT(mAllocatedPointers.Contains(aPtr));
    mAllocatedPointers.RemoveEntry(aPtr);
#endif
  }

public:
  bool AddRefreshObserver(nsARefreshObserver* aObserver,
                          mozFlushType aFlushType) {
#ifdef MOZILLA_INTERNAL_API
    return AddRefreshObserverInternal(aObserver, aFlushType);
#else
    return AddRefreshObserverExternal(aObserver, aFlushType);
#endif
  }

  bool RemoveRefreshObserver(nsARefreshObserver* aObserver,
                             mozFlushType aFlushType) {
#ifdef MOZILLA_INTERNAL_API
    return RemoveRefreshObserverInternal(aObserver, aFlushType);
#else
    return RemoveRefreshObserverExternal(aObserver, aFlushType);
#endif
  }

  virtual bool AddPostRefreshObserver(nsAPostRefreshObserver* aObserver);
  virtual bool RemovePostRefreshObserver(nsAPostRefreshObserver* aObserver);

  /**
   * Initialize and shut down static variables.
   */
  static void InitializeStatics();
  static void ReleaseStatics();

  // If a frame in the subtree rooted at aFrame is capturing the mouse then
  // clears that capture.
  static void ClearMouseCapture(nsIFrame* aFrame);

  void SetScrollPositionClampingScrollPortSize(nscoord aWidth, nscoord aHeight);
  bool IsScrollPositionClampingScrollPortSizeSet() {
    return mScrollPositionClampingScrollPortSizeSet;
  }
  nsSize GetScrollPositionClampingScrollPortSize() {
    NS_ASSERTION(mScrollPositionClampingScrollPortSizeSet, "asking for scroll port when its not set?");
    return mScrollPositionClampingScrollPortSize;
  }

  virtual void WindowSizeMoveDone() = 0;
  virtual void SysColorChanged() = 0;
  virtual void ThemeChanged() = 0;
  virtual void BackingScaleFactorChanged() = 0;

  /**
   * Documents belonging to an invisible DocShell must not be painted ever.
   */
  bool IsNeverPainting() {
    return mIsNeverPainting;
  }

  void SetNeverPainting(bool aNeverPainting) {
    mIsNeverPainting = aNeverPainting;
  }

  bool HasPendingReflow() const
    { return mReflowScheduled || mReflowContinueTimer; }

  void SyncWindowProperties(nsView* aView);

#ifdef ANDROID
  virtual nsIDocument* GetTouchEventTargetDocument() = 0;
#endif

protected:
  friend class nsRefreshDriver;

  // IMPORTANT: The ownership implicit in the following member variables
  // has been explicitly checked.  If you add any members to this class,
  // please make the ownership explicit (pinkerton, scc).

  // These are the same Document and PresContext owned by the DocViewer.
  // we must share ownership.
  nsCOMPtr<nsIDocument>     mDocument;
  RefPtr<nsPresContext>   mPresContext;
  mozilla::StyleSetHandle   mStyleSet;      // [OWNS]
  nsCSSFrameConstructor*    mFrameConstructor; // [OWNS]
  nsViewManager*           mViewManager;   // [WEAK] docViewer owns it so I don't have to
  nsPresArena               mFrameArena;
  RefPtr<nsFrameSelection> mSelection;
  // Pointer into mFrameConstructor - this is purely so that FrameManager() and
  // GetRootFrame() can be inlined:
  nsFrameManagerBase*       mFrameManager;
  mozilla::WeakPtr<nsDocShell>                 mForwardingContainer;
  nsRefreshDriver* MOZ_UNSAFE_REF("These two objects hold weak references "
                                  "to each other, and the validity of this "
                                  "member is ensured by the logic in nsIPresShell.")
                            mHiddenInvalidationObserverRefreshDriver;
#ifdef ACCESSIBILITY
  mozilla::a11y::DocAccessible* mDocAccessible;
#endif

  // At least on Win32 and Mac after interupting a reflow we need to post
  // the resume reflow event off a timer to avoid event starvation because
  // posted messages are processed before other messages when the modal
  // moving/sizing loop is running, see bug 491700 for details.
  nsCOMPtr<nsITimer>        mReflowContinueTimer;

#ifdef DEBUG
  nsIFrame*                 mDrawEventTargetFrame;

  // We track allocated pointers in a debug-only hashtable to assert against
  // missing/double frees.
  nsTHashtable<nsPtrHashKey<void>> mAllocatedPointers;
#endif


  // Count of the number of times this presshell has been painted to a window.
  uint64_t                  mPaintCount;

  nsSize                    mScrollPositionClampingScrollPortSize;

  // A list of weak frames. This is a pointer to the last item in the list.
  nsWeakFrame*              mWeakFrames;

  // Most recent canvas background color.
  nscolor                   mCanvasBackgroundColor;

  // Used to force allocation and rendering of proportionally more or
  // less pixels in both dimensions.
  mozilla::Maybe<float>     mResolution;

  int16_t                   mSelectionFlags;

  // Flags controlling how our document is rendered.  These persist
  // between paints and so are tied with retained layer pixels.
  // PresShell flushes retained layers when the rendering state
  // changes in a way that prevents us from being able to (usefully)
  // re-use old pixels.
  RenderFlags               mRenderFlags;

  // Indicates that the whole document must be restyled.  Changes to scoped
  // style sheets are recorded in mChangedScopeStyleRoots rather than here
  // in mStylesHaveChanged.
  bool                      mStylesHaveChanged : 1;
  bool                      mDidInitialize : 1;
  bool                      mIsDestroying : 1;
  bool                      mIsZombie : 1;
  bool                      mIsReflowing : 1;

  // For all documents we initially lock down painting.
  bool                      mPaintingSuppressed : 1;

  // Whether or not form controls should use nsITheme in this shell.
  bool                      mIsThemeSupportDisabled : 1;

  bool                      mIsActive : 1;
  bool                      mFrozen : 1;
  bool                      mIsFirstPaint : 1;
  bool                      mObservesMutationsForPrint : 1;

  // If true, we have a reflow scheduled. Guaranteed to be false if
  // mReflowContinueTimer is non-null.
  bool                      mReflowScheduled : 1;

  bool                      mSuppressInterruptibleReflows : 1;
  bool                      mScrollPositionClampingScrollPortSizeSet : 1;

  uint32_t                  mPresShellId;

  // List of subtrees rooted at style scope roots that need to be restyled.
  // When a change to a scoped style sheet is made, we add the style scope
  // root to this array rather than setting mStylesHaveChanged = true, since
  // we know we don't need to restyle the whole document.  However, if in the
  // same update block we have already had other changes that require
  // the whole document to be restyled (i.e., mStylesHaveChanged is already
  // true), then we don't bother adding the scope root here.
  AutoTArray<RefPtr<mozilla::dom::Element>,1> mChangedScopeStyleRoots;

  static nsIContent*        gKeyDownTarget;

  // Cached font inflation values. This is done to prevent changing of font
  // inflation until a page is reloaded.
  uint32_t mFontSizeInflationEmPerLine;
  uint32_t mFontSizeInflationMinTwips;
  uint32_t mFontSizeInflationLineThreshold;
  bool mFontSizeInflationForceEnabled;
  bool mFontSizeInflationDisabledInMasterProcess;
  bool mFontSizeInflationEnabled;
  bool mPaintingIsFrozen;

  // Dirty bit indicating that mFontSizeInflationEnabled needs to be recomputed.
  bool mFontSizeInflationEnabledIsDirty;

  // If a document belongs to an invisible DocShell, this flag must be set
  // to true, so we can avoid any paint calls for widget related to this
  // presshell.
  bool mIsNeverPainting;
};

NS_DEFINE_STATIC_IID_ACCESSOR(nsIPresShell, NS_IPRESSHELL_IID)

#endif /* nsIPresShell_h___ */