Add m-esr52 at 52.6.0

1 files changed, 531 insertions, 0 deletions

diff --git a/gfx/layers/apz/src/APZCTreeManager.h b/gfx/layers/apz/src/APZCTreeManager.h
new file mode 100644
index 000000000..c98e292ef
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+++ b/gfx/layers/apz/src/APZCTreeManager.h
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+/* -*- Mode: C++; tab-width: 8; 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/. */
+
+#ifndef mozilla_layers_APZCTreeManager_h
+#define mozilla_layers_APZCTreeManager_h
+
+#include <map>                          // for std::map
+
+#include "gfxPoint.h"                   // for gfxPoint
+#include "mozilla/Assertions.h"         // for MOZ_ASSERT_HELPER2
+#include "mozilla/gfx/Logging.h"        // for gfx::TreeLog
+#include "mozilla/gfx/Matrix.h"         // for Matrix4x4
+#include "mozilla/layers/TouchCounter.h"// for TouchCounter
+#include "mozilla/layers/IAPZCTreeManager.h" // for IAPZCTreeManager
+#include "mozilla/Mutex.h"              // for Mutex
+#include "mozilla/RefPtr.h"             // for RefPtr
+#include "mozilla/TimeStamp.h"          // for mozilla::TimeStamp
+#include "nsCOMPtr.h"                   // for already_AddRefed
+
+
+namespace mozilla {
+class MultiTouchInput;
+
+namespace layers {
+
+class Layer;
+class AsyncPanZoomController;
+class APZCTreeManagerParent;
+class CompositorBridgeParent;
+class OverscrollHandoffChain;
+struct OverscrollHandoffState;
+struct FlingHandoffState;
+class LayerMetricsWrapper;
+class InputQueue;
+class GeckoContentController;
+class HitTestingTreeNode;
+
+/**
+ * ****************** NOTE ON LOCK ORDERING IN APZ **************************
+ *
+ * There are two kinds of locks used by APZ: APZCTreeManager::mTreeLock
+ * ("the tree lock") and AsyncPanZoomController::mMonitor ("APZC locks").
+ *
+ * To avoid deadlock, we impose a lock ordering between these locks, which is:
+ *
+ *      tree lock -> APZC locks
+ *
+ * The interpretation of the lock ordering is that if lock A precedes lock B
+ * in the ordering sequence, then you must NOT wait on A while holding B.
+ *
+ * **************************************************************************
+ */
+
+/**
+ * This class manages the tree of AsyncPanZoomController instances. There is one
+ * instance of this class owned by each CompositorBridgeParent, and it contains as
+ * many AsyncPanZoomController instances as there are scrollable container layers.
+ * This class generally lives on the compositor thread, although some functions
+ * may be called from other threads as noted; thread safety is ensured internally.
+ *
+ * The bulk of the work of this class happens as part of the UpdateHitTestingTree
+ * function, which is when a layer tree update is received by the compositor.
+ * This function walks through the layer tree and creates a tree of
+ * HitTestingTreeNode instances to match the layer tree and for use in
+ * hit-testing on the controller thread. APZC instances may be preserved across
+ * calls to this function if the corresponding layers are still present in the layer
+ * tree.
+ *
+ * The other functions on this class are used by various pieces of client code to
+ * notify the APZC instances of events relevant to them. This includes, for example,
+ * user input events that drive panning and zooming, changes to the scroll viewport
+ * area, and changes to pan/zoom constraints.
+ *
+ * Note that the ClearTree function MUST be called when this class is no longer needed;
+ * see the method documentation for details.
+ *
+ * Behaviour of APZ is controlled by a number of preferences shown \ref APZCPrefs "here".
+ */
+class APZCTreeManager : public IAPZCTreeManager {
+
+  typedef mozilla::layers::AllowedTouchBehavior AllowedTouchBehavior;
+  typedef mozilla::layers::AsyncDragMetrics AsyncDragMetrics;
+
+  // Helper struct to hold some state while we build the hit-testing tree. The
+  // sole purpose of this struct is to shorten the argument list to
+  // UpdateHitTestingTree. All the state that we don't need to
+  // push on the stack during recursion and pop on unwind is stored here.
+  struct TreeBuildingState;
+
+public:
+  APZCTreeManager();
+
+  /**
+   * Initializes the global state used in AsyncPanZoomController.
+   * This is normally called when it is first needed in the constructor
+   * of APZCTreeManager, but can be called manually to force it to be
+   * initialized earlier.
+   */
+  static void InitializeGlobalState();
+
+  /**
+   * Rebuild the hit-testing tree based on the layer update that just came up.
+   * Preserve nodes and APZC instances where possible, but retire those whose
+   * layers are no longer in the layer tree.
+   *
+   * This must be called on the compositor thread as it walks the layer tree.
+   *
+   * @param aRootLayerTreeId The layer tree ID of the root layer corresponding
+   *                         to this APZCTreeManager
+   * @param aRoot The root of the (full) layer tree
+   * @param aFirstPaintLayersId The layers id of the subtree to which aIsFirstPaint
+   *                            applies.
+   * @param aIsFirstPaint True if the layers update that this is called in response
+   *                      to included a first-paint. If this is true, the part of
+   *                      the tree that is affected by the first-paint flag is
+   *                      indicated by the aFirstPaintLayersId parameter.
+   * @param aPaintSequenceNumber The sequence number of the paint that triggered
+   *                             this layer update. Note that every layer child
+   *                             process' layer subtree has its own sequence
+   *                             numbers.
+   */
+  void UpdateHitTestingTree(uint64_t aRootLayerTreeId,
+                            Layer* aRoot,
+                            bool aIsFirstPaint,
+                            uint64_t aOriginatingLayersId,
+                            uint32_t aPaintSequenceNumber);
+
+  /**
+   * Walk the tree of APZCs and flushes the repaint requests for all the APZCS
+   * corresponding to the given layers id. Finally, sends a flush complete
+   * notification to the GeckoContentController for the layers id.
+   */
+  void FlushApzRepaints(uint64_t aLayersId);
+
+  /**
+   * General handler for incoming input events. Manipulates the frame metrics
+   * based on what type of input it is. For example, a PinchGestureEvent will
+   * cause scaling. This should only be called externally to this class, and
+   * must be called on the controller thread.
+   *
+   * This function transforms |aEvent| to have its coordinates in DOM space.
+   * This is so that the event can be passed through the DOM and content can
+   * handle them. The event may need to be converted to a WidgetInputEvent
+   * by the caller if it wants to do this.
+   *
+   * The following values may be returned by this function:
+   * nsEventStatus_eConsumeNoDefault is returned to indicate the
+   *   APZ is consuming this event and the caller should discard the event with
+   *   extreme prejudice. The exact scenarios under which this is returned is
+   *   implementation-dependent and may vary.
+   * nsEventStatus_eIgnore is returned to indicate that the APZ code didn't
+   *   use this event. This might be because it was directed at a point on
+   *   the screen where there was no APZ, or because the thing the user was
+   *   trying to do was not allowed. (For example, attempting to pan a
+   *   non-pannable document).
+   * nsEventStatus_eConsumeDoDefault is returned to indicate that the APZ
+   *   code may have used this event to do some user-visible thing. Note that
+   *   in some cases CONSUMED is returned even if the event was NOT used. This
+   *   is because we cannot always know at the time of event delivery whether
+   *   the event will be used or not. So we err on the side of sending
+   *   CONSUMED when we are uncertain.
+   *
+   * @param aEvent input event object; is modified in-place
+   * @param aOutTargetGuid returns the guid of the apzc this event was
+   * delivered to. May be null.
+   * @param aOutInputBlockId returns the id of the input block that this event
+   * was added to, if that was the case. May be null.
+   */
+  nsEventStatus ReceiveInputEvent(
+      InputData& aEvent,
+      ScrollableLayerGuid* aOutTargetGuid,
+      uint64_t* aOutInputBlockId) override;
+
+  /**
+   * Kicks an animation to zoom to a rect. This may be either a zoom out or zoom
+   * in. The actual animation is done on the compositor thread after being set
+   * up. |aRect| must be given in CSS pixels, relative to the document.
+   * |aFlags| is a combination of the ZoomToRectBehavior enum values.
+   */
+  void ZoomToRect(
+      const ScrollableLayerGuid& aGuid,
+      const CSSRect& aRect,
+      const uint32_t aFlags = DEFAULT_BEHAVIOR) override;
+
+  /**
+   * If we have touch listeners, this should always be called when we know
+   * definitively whether or not content has preventDefaulted any touch events
+   * that have come in. If |aPreventDefault| is true, any touch events in the
+   * queue will be discarded. This function must be called on the controller
+   * thread.
+   */
+  void ContentReceivedInputBlock(
+      uint64_t aInputBlockId,
+      bool aPreventDefault) override;
+
+  /**
+   * When the event regions code is enabled, this function should be invoked to
+   * to confirm the target of the input block. This is only needed in cases
+   * where the initial input event of the block hit a dispatch-to-content region
+   * but is safe to call for all input blocks. This function should always be
+   * invoked on the controller thread.
+   * The different elements in the array of targets correspond to the targets
+   * for the different touch points. In the case where the touch point has no
+   * target, or the target is not a scrollable frame, the target's |mScrollId|
+   * should be set to FrameMetrics::NULL_SCROLL_ID.
+   */
+  void SetTargetAPZC(
+      uint64_t aInputBlockId,
+      const nsTArray<ScrollableLayerGuid>& aTargets) override;
+
+  /**
+   * Helper function for SetTargetAPZC when used with single-target events,
+   * such as mouse wheel events.
+   */
+  void SetTargetAPZC(uint64_t aInputBlockId, const ScrollableLayerGuid& aTarget);
+
+  /**
+   * Updates any zoom constraints contained in the <meta name="viewport"> tag.
+   * If the |aConstraints| is Nothing() then previously-provided constraints for
+   * the given |aGuid| are cleared.
+   */
+  void UpdateZoomConstraints(
+      const ScrollableLayerGuid& aGuid,
+      const Maybe<ZoomConstraints>& aConstraints) override;
+
+  /**
+   * Cancels any currently running animation. Note that all this does is set the
+   * state of the AsyncPanZoomController back to NOTHING, but it is the
+   * animation's responsibility to check this before advancing.
+   */
+  void CancelAnimation(const ScrollableLayerGuid &aGuid) override;
+
+  /**
+   * Adjusts the root APZC to compensate for a shift in the surface. See the
+   * documentation on AsyncPanZoomController::AdjustScrollForSurfaceShift for
+   * some more details. This is only currently needed due to surface shifts
+   * caused by the dynamic toolbar on Android.
+   */
+  void AdjustScrollForSurfaceShift(const ScreenPoint& aShift) override;
+
+  /**
+   * Calls Destroy() on all APZC instances attached to the tree, and resets the
+   * tree back to empty. This function must be called exactly once during the
+   * lifetime of this APZCTreeManager, when this APZCTreeManager is no longer
+   * needed. Failing to call this function may prevent objects from being freed
+   * properly.
+   */
+  void ClearTree();
+
+  /**
+   * Tests if a screen point intersect an apz in the tree.
+   */
+  bool HitTestAPZC(const ScreenIntPoint& aPoint);
+
+  /**
+   * See AsyncPanZoomController::CalculatePendingDisplayPort. This
+   * function simply delegates to that one, so that non-layers code
+   * never needs to include AsyncPanZoomController.h
+   */
+  static const ScreenMargin CalculatePendingDisplayPort(
+    const FrameMetrics& aFrameMetrics,
+    const ParentLayerPoint& aVelocity);
+
+  /**
+   * Sets the dpi value used by all AsyncPanZoomControllers.
+   * DPI defaults to 72 if not set using SetDPI() at any point.
+   */
+  void SetDPI(float aDpiValue) override { sDPI = aDpiValue; }
+
+  /**
+   * Returns the current dpi value in use.
+   */
+  static float GetDPI() { return sDPI; }
+
+  /**
+   * Find the hit testing node for the scrollbar thumb that matches these
+   * drag metrics.
+   */
+  RefPtr<HitTestingTreeNode> FindScrollNode(const AsyncDragMetrics& aDragMetrics);
+
+  /**
+   * Sets allowed touch behavior values for current touch-session for specific
+   * input block (determined by aInputBlock).
+   * Should be invoked by the widget. Each value of the aValues arrays
+   * corresponds to the different touch point that is currently active.
+   * Must be called after receiving the TOUCH_START event that starts the
+   * touch-session.
+   * This must be called on the controller thread.
+   */
+  void SetAllowedTouchBehavior(
+      uint64_t aInputBlockId,
+      const nsTArray<TouchBehaviorFlags>& aValues) override;
+
+  /**
+   * This is a callback for AsyncPanZoomController to call when it wants to
+   * scroll in response to a touch-move event, or when it needs to hand off
+   * overscroll to the next APZC. Note that because of scroll grabbing, the
+   * first APZC to scroll may not be the one that is receiving the touch events.
+   *
+   * |aAPZC| is the APZC that received the touch events triggering the scroll
+   *   (in the case of an initial scroll), or the last APZC to scroll (in the
+   *   case of overscroll)
+   * |aStartPoint| and |aEndPoint| are in |aAPZC|'s transformed screen
+   *   coordinates (i.e. the same coordinates in which touch points are given to
+   *   APZCs). The amount of (over)scroll is represented by two points rather
+   *   than a displacement because with certain 3D transforms, the same
+   *   displacement between different points in transformed coordinates can
+   *   represent different displacements in untransformed coordinates.
+   * |aOverscrollHandoffChain| is the overscroll handoff chain used for
+   *   determining the order in which scroll should be handed off between
+   *   APZCs
+   * |aOverscrollHandoffChainIndex| is the next position in the overscroll
+   *   handoff chain that should be scrolled.
+   *
+   * aStartPoint and aEndPoint will be modified depending on how much of the
+   * scroll each APZC consumes. This is to allow the sending APZC to go into
+   * an overscrolled state if no APZC further up in the handoff chain accepted
+   * the entire scroll.
+   *
+   * The way this method works is best illustrated with an example.
+   * Consider three nested APZCs, A, B, and C, with C being the innermost one.
+   * Say B is scroll-grabbing.
+   * The touch events go to C because it's the innermost one (so e.g. taps
+   * should go through C), but the overscroll handoff chain is B -> C -> A
+   * because B is scroll-grabbing.
+   * For convenience I'll refer to the three APZC objects as A, B, and C, and
+   * to the tree manager object as TM.
+   * Here's what happens when C receives a touch-move event:
+   *   - C.TrackTouch() calls TM.DispatchScroll() with index = 0.
+   *   - TM.DispatchScroll() calls B.AttemptScroll() (since B is at index 0 in the chain).
+   *   - B.AttemptScroll() scrolls B. If there is overscroll, it calls TM.DispatchScroll() with index = 1.
+   *   - TM.DispatchScroll() calls C.AttemptScroll() (since C is at index 1 in the chain)
+   *   - C.AttemptScroll() scrolls C. If there is overscroll, it calls TM.DispatchScroll() with index = 2.
+   *   - TM.DispatchScroll() calls A.AttemptScroll() (since A is at index 2 in the chain)
+   *   - A.AttemptScroll() scrolls A. If there is overscroll, it calls TM.DispatchScroll() with index = 3.
+   *   - TM.DispatchScroll() discards the rest of the scroll as there are no more elements in the chain.
+   *
+   * Note: this should be used for panning only. For handing off overscroll for
+   *       a fling, use DispatchFling().
+   */
+  void DispatchScroll(AsyncPanZoomController* aApzc,
+                      ParentLayerPoint& aStartPoint,
+                      ParentLayerPoint& aEndPoint,
+                      OverscrollHandoffState& aOverscrollHandoffState);
+
+  /**
+   * This is a callback for AsyncPanZoomController to call when it wants to
+   * start a fling in response to a touch-end event, or when it needs to hand
+   * off a fling to the next APZC. Note that because of scroll grabbing, the
+   * first APZC to fling may not be the one that is receiving the touch events.
+   *
+   * @param aApzc the APZC that wants to start or hand off the fling
+   * @param aHandoffState a collection of state about the operation,
+   *                      which contains the following:
+   *
+   *        mVelocity the current velocity of the fling, in |aApzc|'s screen
+   *                  pixels per millisecond
+   *        mChain the chain of APZCs along which the fling
+   *                   should be handed off
+   *        mIsHandoff is true if |aApzc| is handing off an existing fling (in
+   *                   this case the fling is given to the next APZC in the
+   *                   handoff chain after |aApzc|), and false is |aApzc| wants
+   *                   start a fling (in this case the fling is given to the
+   *                   first APZC in the chain)
+   *
+   * aHandoffState.mVelocity will be modified depending on how much of that
+   * velocity has been consumed by APZCs in the overscroll hand-off chain.
+   * The caller can use this value to determine whether it should consume
+   * the excess velocity by going into an overscroll fling.
+   */
+  void DispatchFling(AsyncPanZoomController* aApzc,
+                     FlingHandoffState& aHandoffState);
+
+  void StartScrollbarDrag(
+      const ScrollableLayerGuid& aGuid,
+      const AsyncDragMetrics& aDragMetrics) override;
+
+  /*
+   * Build the chain of APZCs that will handle overscroll for a pan starting at |aInitialTarget|.
+   */
+  RefPtr<const OverscrollHandoffChain> BuildOverscrollHandoffChain(const RefPtr<AsyncPanZoomController>& aInitialTarget);
+
+  /**
+   * Function used to disable LongTap gestures.
+   *
+   * On slow running tests, drags and touch events can be misinterpreted
+   * as a long tap. This allows tests to disable long tap gesture detection.
+   */
+  void SetLongTapEnabled(bool aTapGestureEnabled) override;
+
+  // Methods to help process WidgetInputEvents (or manage conversion to/from InputData)
+
+  void TransformEventRefPoint(
+      LayoutDeviceIntPoint* aRefPoint,
+      ScrollableLayerGuid* aOutTargetGuid) override;
+
+  void UpdateWheelTransaction(
+      LayoutDeviceIntPoint aRefPoint,
+      EventMessage aEventMessage) override;
+
+protected:
+  // Protected destructor, to discourage deletion outside of Release():
+  virtual ~APZCTreeManager();
+
+  // Protected hooks for gtests subclass
+  virtual AsyncPanZoomController* NewAPZCInstance(uint64_t aLayersId,
+                                                  GeckoContentController* aController);
+public:
+  // Public hooks for gtests subclass
+  virtual TimeStamp GetFrameTime();
+
+public:
+  /* Some helper functions to find an APZC given some identifying input. These functions
+     lock the tree of APZCs while they find the right one, and then return an addref'd
+     pointer to it. This allows caller code to just use the target APZC without worrying
+     about it going away. These are public for testing code and generally should not be
+     used by other production code.
+  */
+  RefPtr<HitTestingTreeNode> GetRootNode() const;
+  already_AddRefed<AsyncPanZoomController> GetTargetAPZC(const ScreenPoint& aPoint,
+                                                         HitTestResult* aOutHitResult,
+                                                         bool* aOutHitScrollbar = nullptr);
+  ScreenToParentLayerMatrix4x4 GetScreenToApzcTransform(const AsyncPanZoomController *aApzc) const;
+  ParentLayerToScreenMatrix4x4 GetApzcToGeckoTransform(const AsyncPanZoomController *aApzc) const;
+
+  /**
+   * Process touch velocity.
+   * Sometimes the touch move event will have a velocity even though no scrolling
+   * is occurring such as when the toolbar is being hidden/shown in Fennec.
+   * This function can be called to have the y axis' velocity queue updated.
+   */
+  void ProcessTouchVelocity(uint32_t aTimestampMs, float aSpeedY) override;
+private:
+  typedef bool (*GuidComparator)(const ScrollableLayerGuid&, const ScrollableLayerGuid&);
+
+  /* Helpers */
+  void AttachNodeToTree(HitTestingTreeNode* aNode,
+                        HitTestingTreeNode* aParent,
+                        HitTestingTreeNode* aNextSibling);
+  already_AddRefed<AsyncPanZoomController> GetTargetAPZC(const ScrollableLayerGuid& aGuid);
+  already_AddRefed<HitTestingTreeNode> GetTargetNode(const ScrollableLayerGuid& aGuid,
+                                                     GuidComparator aComparator);
+  HitTestingTreeNode* FindTargetNode(HitTestingTreeNode* aNode,
+                                     const ScrollableLayerGuid& aGuid,
+                                     GuidComparator aComparator);
+  AsyncPanZoomController* GetTargetApzcForNode(HitTestingTreeNode* aNode);
+  AsyncPanZoomController* GetAPZCAtPoint(HitTestingTreeNode* aNode,
+                                         const ParentLayerPoint& aHitTestPoint,
+                                         HitTestResult* aOutHitResult,
+                                         bool* aOutHitScrollbar);
+  AsyncPanZoomController* FindRootApzcForLayersId(uint64_t aLayersId) const;
+  AsyncPanZoomController* FindRootContentApzcForLayersId(uint64_t aLayersId) const;
+  AsyncPanZoomController* FindRootContentOrRootApzc() const;
+  already_AddRefed<AsyncPanZoomController> GetMultitouchTarget(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const;
+  already_AddRefed<AsyncPanZoomController> CommonAncestor(AsyncPanZoomController* aApzc1, AsyncPanZoomController* aApzc2) const;
+  already_AddRefed<AsyncPanZoomController> GetTouchInputBlockAPZC(const MultiTouchInput& aEvent,
+                                                                  nsTArray<TouchBehaviorFlags>* aOutTouchBehaviors,
+                                                                  HitTestResult* aOutHitResult);
+  nsEventStatus ProcessTouchInput(MultiTouchInput& aInput,
+                                  ScrollableLayerGuid* aOutTargetGuid,
+                                  uint64_t* aOutInputBlockId);
+  void FlushRepaintsToClearScreenToGeckoTransform();
+
+  already_AddRefed<HitTestingTreeNode> RecycleOrCreateNode(TreeBuildingState& aState,
+                                                           AsyncPanZoomController* aApzc,
+                                                           uint64_t aLayersId);
+  HitTestingTreeNode* PrepareNodeForLayer(const LayerMetricsWrapper& aLayer,
+                                          const FrameMetrics& aMetrics,
+                                          uint64_t aLayersId,
+                                          const gfx::Matrix4x4& aAncestorTransform,
+                                          HitTestingTreeNode* aParent,
+                                          HitTestingTreeNode* aNextSibling,
+                                          TreeBuildingState& aState);
+
+  void PrintAPZCInfo(const LayerMetricsWrapper& aLayer,
+                     const AsyncPanZoomController* apzc);
+
+protected:
+  /* The input queue where input events are held until we know enough to
+   * figure out where they're going. Protected so gtests can access it.
+   */
+  RefPtr<InputQueue> mInputQueue;
+
+private:
+  /* Whenever walking or mutating the tree rooted at mRootNode, mTreeLock must be held.
+   * This lock does not need to be held while manipulating a single APZC instance in
+   * isolation (that is, if its tree pointers are not being accessed or mutated). The
+   * lock also needs to be held when accessing the mRootNode instance variable, as that
+   * is considered part of the APZC tree management state.
+   * Finally, the lock needs to be held when accessing mZoomConstraints.
+   * IMPORTANT: See the note about lock ordering at the top of this file. */
+  mutable mozilla::Mutex mTreeLock;
+  RefPtr<HitTestingTreeNode> mRootNode;
+  /* Holds the zoom constraints for scrollable layers, as determined by the
+   * the main-thread gecko code. */
+  std::map<ScrollableLayerGuid, ZoomConstraints> mZoomConstraints;
+  /* This tracks the APZC that should receive all inputs for the current input event block.
+   * This allows touch points to move outside the thing they started on, but still have the
+   * touch events delivered to the same initial APZC. This will only ever be touched on the
+   * input delivery thread, and so does not require locking.
+   */
+  RefPtr<AsyncPanZoomController> mApzcForInputBlock;
+  /* The hit result for the current input event block; this should always be in
+   * sync with mApzcForInputBlock.
+   */
+  HitTestResult mHitResultForInputBlock;
+  /* Sometimes we want to ignore all touches except one. In such cases, this
+   * is set to the identifier of the touch we are not ignoring; in other cases,
+   * this is set to -1.
+   */
+  int32_t mRetainedTouchIdentifier;
+  /* Tracks the number of touch points we are tracking that are currently on
+   * the screen. */
+  TouchCounter mTouchCounter;
+  /* For logging the APZC tree for debugging (enabled by the apz.printtree
+   * pref). */
+  gfx::TreeLog mApzcTreeLog;
+
+  class CheckerboardFlushObserver;
+  friend class CheckerboardFlushObserver;
+  RefPtr<CheckerboardFlushObserver> mFlushObserver;
+
+  static float sDPI;
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif // mozilla_layers_PanZoomController_h