Add m-esr52 at 52.6.0

1 files changed, 521 insertions, 0 deletions

diff --git a/gfx/layers/apz/test/gtest/TestScrollHandoff.cpp b/gfx/layers/apz/test/gtest/TestScrollHandoff.cpp
new file mode 100644
index 000000000..d57d09ead
--- /dev/null
+++ b/gfx/layers/apz/test/gtest/TestScrollHandoff.cpp
@@ -0,0 +1,521 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+/* 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/. */
+
+#include "APZCTreeManagerTester.h"
+#include "APZTestCommon.h"
+#include "InputUtils.h"
+
+class APZScrollHandoffTester : public APZCTreeManagerTester {
+protected:
+  UniquePtr<ScopedLayerTreeRegistration> registration;
+  TestAsyncPanZoomController* rootApzc;
+
+  void CreateScrollHandoffLayerTree1() {
+    const char* layerTreeSyntax = "c(t)";
+    nsIntRegion layerVisibleRegion[] = {
+      nsIntRegion(IntRect(0, 0, 100, 100)),
+      nsIntRegion(IntRect(0, 50, 100, 50))
+    };
+    root = CreateLayerTree(layerTreeSyntax, layerVisibleRegion, nullptr, lm, layers);
+    SetScrollableFrameMetrics(root, FrameMetrics::START_SCROLL_ID, CSSRect(0, 0, 200, 200));
+    SetScrollableFrameMetrics(layers[1], FrameMetrics::START_SCROLL_ID + 1, CSSRect(0, 0, 100, 100));
+    SetScrollHandoff(layers[1], root);
+    registration = MakeUnique<ScopedLayerTreeRegistration>(manager, 0, root, mcc);
+    manager->UpdateHitTestingTree(0, root, false, 0, 0);
+    rootApzc = ApzcOf(root);
+    rootApzc->GetFrameMetrics().SetIsRootContent(true);  // make root APZC zoomable
+  }
+
+  void CreateScrollHandoffLayerTree2() {
+    const char* layerTreeSyntax = "c(c(t))";
+    nsIntRegion layerVisibleRegion[] = {
+      nsIntRegion(IntRect(0, 0, 100, 100)),
+      nsIntRegion(IntRect(0, 0, 100, 100)),
+      nsIntRegion(IntRect(0, 50, 100, 50))
+    };
+    root = CreateLayerTree(layerTreeSyntax, layerVisibleRegion, nullptr, lm, layers);
+    SetScrollableFrameMetrics(root, FrameMetrics::START_SCROLL_ID, CSSRect(0, 0, 200, 200));
+    SetScrollableFrameMetrics(layers[1], FrameMetrics::START_SCROLL_ID + 2, CSSRect(-100, -100, 200, 200));
+    SetScrollableFrameMetrics(layers[2], FrameMetrics::START_SCROLL_ID + 1, CSSRect(0, 0, 100, 100));
+    SetScrollHandoff(layers[1], root);
+    SetScrollHandoff(layers[2], layers[1]);
+    // No ScopedLayerTreeRegistration as that just needs to be done once per test
+    // and this is the second layer tree for a particular test.
+    MOZ_ASSERT(registration);
+    manager->UpdateHitTestingTree(0, root, false, 0, 0);
+    rootApzc = ApzcOf(root);
+  }
+
+  void CreateScrollHandoffLayerTree3() {
+    const char* layerTreeSyntax = "c(c(t)c(t))";
+    nsIntRegion layerVisibleRegion[] = {
+      nsIntRegion(IntRect(0, 0, 100, 100)),  // root
+      nsIntRegion(IntRect(0, 0, 100, 50)),   // scrolling parent 1
+      nsIntRegion(IntRect(0, 0, 100, 50)),   // scrolling child 1
+      nsIntRegion(IntRect(0, 50, 100, 50)),  // scrolling parent 2
+      nsIntRegion(IntRect(0, 50, 100, 50))   // scrolling child 2
+    };
+    root = CreateLayerTree(layerTreeSyntax, layerVisibleRegion, nullptr, lm, layers);
+    SetScrollableFrameMetrics(layers[0], FrameMetrics::START_SCROLL_ID, CSSRect(0, 0, 100, 100));
+    SetScrollableFrameMetrics(layers[1], FrameMetrics::START_SCROLL_ID + 1, CSSRect(0, 0, 100, 100));
+    SetScrollableFrameMetrics(layers[2], FrameMetrics::START_SCROLL_ID + 2, CSSRect(0, 0, 100, 100));
+    SetScrollableFrameMetrics(layers[3], FrameMetrics::START_SCROLL_ID + 3, CSSRect(0, 50, 100, 100));
+    SetScrollableFrameMetrics(layers[4], FrameMetrics::START_SCROLL_ID + 4, CSSRect(0, 50, 100, 100));
+    SetScrollHandoff(layers[1], layers[0]);
+    SetScrollHandoff(layers[3], layers[0]);
+    SetScrollHandoff(layers[2], layers[1]);
+    SetScrollHandoff(layers[4], layers[3]);
+    registration = MakeUnique<ScopedLayerTreeRegistration>(manager, 0, root, mcc);
+    manager->UpdateHitTestingTree(0, root, false, 0, 0);
+  }
+
+  void CreateScrollgrabLayerTree(bool makeParentScrollable = true) {
+    const char* layerTreeSyntax = "c(t)";
+    nsIntRegion layerVisibleRegion[] = {
+      nsIntRegion(IntRect(0, 0, 100, 100)),  // scroll-grabbing parent
+      nsIntRegion(IntRect(0, 20, 100, 80))   // child
+    };
+    root = CreateLayerTree(layerTreeSyntax, layerVisibleRegion, nullptr, lm, layers);
+    float parentHeight = makeParentScrollable ? 120 : 100;
+    SetScrollableFrameMetrics(root, FrameMetrics::START_SCROLL_ID, CSSRect(0, 0, 100, parentHeight));
+    SetScrollableFrameMetrics(layers[1], FrameMetrics::START_SCROLL_ID + 1, CSSRect(0, 0, 100, 200));
+    SetScrollHandoff(layers[1], root);
+    registration = MakeUnique<ScopedLayerTreeRegistration>(manager, 0, root, mcc);
+    manager->UpdateHitTestingTree(0, root, false, 0, 0);
+    rootApzc = ApzcOf(root);
+    rootApzc->GetScrollMetadata().SetHasScrollgrab(true);
+  }
+
+  void TestFlingAcceleration() {
+    // Jack up the fling acceleration multiplier so we can easily determine
+    // whether acceleration occured.
+    const float kAcceleration = 100.0f;
+    SCOPED_GFX_PREF(APZFlingAccelBaseMultiplier, float, kAcceleration);
+    SCOPED_GFX_PREF(APZFlingAccelMinVelocity, float, 0.0);
+
+    RefPtr<TestAsyncPanZoomController> childApzc = ApzcOf(layers[1]);
+
+    // Pan once, enough to fully scroll the scrollgrab parent and then scroll
+    // and fling the child.
+    Pan(manager, 70, 40);
+
+    // Give the fling animation a chance to start.
+    SampleAnimationsOnce();
+
+    float childVelocityAfterFling1 = childApzc->GetVelocityVector().y;
+
+    // Pan again.
+    Pan(manager, 70, 40);
+
+    // Give the fling animation a chance to start.
+    // This time it should be accelerated.
+    SampleAnimationsOnce();
+
+    float childVelocityAfterFling2 = childApzc->GetVelocityVector().y;
+
+    // We should have accelerated once.
+    // The division by 2 is to account for friction.
+    EXPECT_GT(childVelocityAfterFling2,
+              childVelocityAfterFling1 * kAcceleration / 2);
+
+    // We should not have accelerated twice.
+    // The division by 4 is to account for friction.
+    EXPECT_LE(childVelocityAfterFling2,
+              childVelocityAfterFling1 * kAcceleration * kAcceleration / 4);
+  }
+};
+
+// Here we test that if the processing of a touch block is deferred while we
+// wait for content to send a prevent-default message, overscroll is still
+// handed off correctly when the block is processed.
+TEST_F(APZScrollHandoffTester, DeferredInputEventProcessing) {
+  // Set up the APZC tree.
+  CreateScrollHandoffLayerTree1();
+
+  TestAsyncPanZoomController* childApzc = ApzcOf(layers[1]);
+
+  // Enable touch-listeners so that we can separate the queueing of input
+  // events from them being processed.
+  childApzc->SetWaitForMainThread();
+
+  // Queue input events for a pan.
+  uint64_t blockId = 0;
+  ApzcPanNoFling(childApzc, 90, 30, &blockId);
+
+  // Allow the pan to be processed.
+  childApzc->ContentReceivedInputBlock(blockId, false);
+  childApzc->ConfirmTarget(blockId);
+
+  // Make sure overscroll was handed off correctly.
+  EXPECT_EQ(50, childApzc->GetFrameMetrics().GetScrollOffset().y);
+  EXPECT_EQ(10, rootApzc->GetFrameMetrics().GetScrollOffset().y);
+}
+
+// Here we test that if the layer structure changes in between two input
+// blocks being queued, and the first block is only processed after the second
+// one has been queued, overscroll handoff for the first block follows
+// the original layer structure while overscroll handoff for the second block
+// follows the new layer structure.
+TEST_F(APZScrollHandoffTester, LayerStructureChangesWhileEventsArePending) {
+  // Set up an initial APZC tree.
+  CreateScrollHandoffLayerTree1();
+
+  TestAsyncPanZoomController* childApzc = ApzcOf(layers[1]);
+
+  // Enable touch-listeners so that we can separate the queueing of input
+  // events from them being processed.
+  childApzc->SetWaitForMainThread();
+
+  // Queue input events for a pan.
+  uint64_t blockId = 0;
+  ApzcPanNoFling(childApzc, 90, 30, &blockId);
+
+  // Modify the APZC tree to insert a new APZC 'middle' into the handoff chain
+  // between the child and the root.
+  CreateScrollHandoffLayerTree2();
+  RefPtr<Layer> middle = layers[1];
+  childApzc->SetWaitForMainThread();
+  TestAsyncPanZoomController* middleApzc = ApzcOf(middle);
+
+  // Queue input events for another pan.
+  uint64_t secondBlockId = 0;
+  ApzcPanNoFling(childApzc, 30, 90, &secondBlockId);
+
+  // Allow the first pan to be processed.
+  childApzc->ContentReceivedInputBlock(blockId, false);
+  childApzc->ConfirmTarget(blockId);
+
+  // Make sure things have scrolled according to the handoff chain in
+  // place at the time the touch-start of the first pan was queued.
+  EXPECT_EQ(50, childApzc->GetFrameMetrics().GetScrollOffset().y);
+  EXPECT_EQ(10, rootApzc->GetFrameMetrics().GetScrollOffset().y);
+  EXPECT_EQ(0, middleApzc->GetFrameMetrics().GetScrollOffset().y);
+
+  // Allow the second pan to be processed.
+  childApzc->ContentReceivedInputBlock(secondBlockId, false);
+  childApzc->ConfirmTarget(secondBlockId);
+
+  // Make sure things have scrolled according to the handoff chain in
+  // place at the time the touch-start of the second pan was queued.
+  EXPECT_EQ(0, childApzc->GetFrameMetrics().GetScrollOffset().y);
+  EXPECT_EQ(10, rootApzc->GetFrameMetrics().GetScrollOffset().y);
+  EXPECT_EQ(-10, middleApzc->GetFrameMetrics().GetScrollOffset().y);
+}
+
+// Test that putting a second finger down on an APZC while a down-chain APZC
+// is overscrolled doesn't result in being stuck in overscroll.
+TEST_F(APZScrollHandoffTester, StuckInOverscroll_Bug1073250) {
+  // Enable overscrolling.
+  SCOPED_GFX_PREF(APZOverscrollEnabled, bool, true);
+  SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
+
+  CreateScrollHandoffLayerTree1();
+
+  TestAsyncPanZoomController* child = ApzcOf(layers[1]);
+
+  // Pan, causing the parent APZC to overscroll.
+  Pan(manager, 10, 40, true /* keep finger down */);
+  EXPECT_FALSE(child->IsOverscrolled());
+  EXPECT_TRUE(rootApzc->IsOverscrolled());
+
+  // Put a second finger down.
+  MultiTouchInput secondFingerDown(MultiTouchInput::MULTITOUCH_START, 0, TimeStamp(), 0);
+  // Use the same touch identifier for the first touch (0) as Pan(). (A bit hacky.)
+  secondFingerDown.mTouches.AppendElement(SingleTouchData(0, ScreenIntPoint(10, 40), ScreenSize(0, 0), 0, 0));
+  secondFingerDown.mTouches.AppendElement(SingleTouchData(1, ScreenIntPoint(30, 20), ScreenSize(0, 0), 0, 0));
+  manager->ReceiveInputEvent(secondFingerDown, nullptr, nullptr);
+
+  // Release the fingers.
+  MultiTouchInput fingersUp = secondFingerDown;
+  fingersUp.mType = MultiTouchInput::MULTITOUCH_END;
+  manager->ReceiveInputEvent(fingersUp, nullptr, nullptr);
+
+  // Allow any animations to run their course.
+  child->AdvanceAnimationsUntilEnd();
+  rootApzc->AdvanceAnimationsUntilEnd();
+
+  // Make sure nothing is overscrolled.
+  EXPECT_FALSE(child->IsOverscrolled());
+  EXPECT_FALSE(rootApzc->IsOverscrolled());
+}
+
+// This is almost exactly like StuckInOverscroll_Bug1073250, except the
+// APZC receiving the input events for the first touch block is the child
+// (and thus not the same APZC that overscrolls, which is the parent).
+TEST_F(APZScrollHandoffTester, StuckInOverscroll_Bug1231228) {
+  // Enable overscrolling.
+  SCOPED_GFX_PREF(APZOverscrollEnabled, bool, true);
+  SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
+
+  CreateScrollHandoffLayerTree1();
+
+  TestAsyncPanZoomController* child = ApzcOf(layers[1]);
+
+  // Pan, causing the parent APZC to overscroll.
+  Pan(manager, 60, 90, true /* keep finger down */);
+  EXPECT_FALSE(child->IsOverscrolled());
+  EXPECT_TRUE(rootApzc->IsOverscrolled());
+
+  // Put a second finger down.
+  MultiTouchInput secondFingerDown(MultiTouchInput::MULTITOUCH_START, 0, TimeStamp(), 0);
+  // Use the same touch identifier for the first touch (0) as Pan(). (A bit hacky.)
+  secondFingerDown.mTouches.AppendElement(SingleTouchData(0, ScreenIntPoint(10, 40), ScreenSize(0, 0), 0, 0));
+  secondFingerDown.mTouches.AppendElement(SingleTouchData(1, ScreenIntPoint(30, 20), ScreenSize(0, 0), 0, 0));
+  manager->ReceiveInputEvent(secondFingerDown, nullptr, nullptr);
+
+  // Release the fingers.
+  MultiTouchInput fingersUp = secondFingerDown;
+  fingersUp.mType = MultiTouchInput::MULTITOUCH_END;
+  manager->ReceiveInputEvent(fingersUp, nullptr, nullptr);
+
+  // Allow any animations to run their course.
+  child->AdvanceAnimationsUntilEnd();
+  rootApzc->AdvanceAnimationsUntilEnd();
+
+  // Make sure nothing is overscrolled.
+  EXPECT_FALSE(child->IsOverscrolled());
+  EXPECT_FALSE(rootApzc->IsOverscrolled());
+}
+
+TEST_F(APZScrollHandoffTester, StuckInOverscroll_Bug1240202a) {
+  // Enable overscrolling.
+  SCOPED_GFX_PREF(APZOverscrollEnabled, bool, true);
+
+  CreateScrollHandoffLayerTree1();
+
+  TestAsyncPanZoomController* child = ApzcOf(layers[1]);
+
+  // Pan, causing the parent APZC to overscroll.
+  Pan(manager, 60, 90, true /* keep finger down */);
+  EXPECT_FALSE(child->IsOverscrolled());
+  EXPECT_TRUE(rootApzc->IsOverscrolled());
+
+  // Lift the finger, triggering an overscroll animation
+  // (but don't allow it to run).
+  TouchUp(manager, ScreenIntPoint(10, 90), mcc->Time());
+
+  // Put the finger down again, interrupting the animation
+  // and entering the TOUCHING state.
+  TouchDown(manager, ScreenIntPoint(10, 90), mcc->Time());
+
+  // Lift the finger once again.
+  TouchUp(manager, ScreenIntPoint(10, 90), mcc->Time());
+
+  // Allow any animations to run their course.
+  child->AdvanceAnimationsUntilEnd();
+  rootApzc->AdvanceAnimationsUntilEnd();
+
+  // Make sure nothing is overscrolled.
+  EXPECT_FALSE(child->IsOverscrolled());
+  EXPECT_FALSE(rootApzc->IsOverscrolled());
+}
+
+TEST_F(APZScrollHandoffTester, StuckInOverscroll_Bug1240202b) {
+  // Enable overscrolling.
+  SCOPED_GFX_PREF(APZOverscrollEnabled, bool, true);
+
+  CreateScrollHandoffLayerTree1();
+
+  TestAsyncPanZoomController* child = ApzcOf(layers[1]);
+
+  // Pan, causing the parent APZC to overscroll.
+  Pan(manager, 60, 90, true /* keep finger down */);
+  EXPECT_FALSE(child->IsOverscrolled());
+  EXPECT_TRUE(rootApzc->IsOverscrolled());
+
+  // Lift the finger, triggering an overscroll animation
+  // (but don't allow it to run).
+  TouchUp(manager, ScreenIntPoint(10, 90), mcc->Time());
+
+  // Put the finger down again, interrupting the animation
+  // and entering the TOUCHING state.
+  TouchDown(manager, ScreenIntPoint(10, 90), mcc->Time());
+
+  // Put a second finger down. Since we're in the TOUCHING state,
+  // the "are we panned into overscroll" check will fail and we
+  // will not ignore the second finger, instead entering the
+  // PINCHING state.
+  MultiTouchInput secondFingerDown(MultiTouchInput::MULTITOUCH_START, 0, TimeStamp(), 0);
+  // Use the same touch identifier for the first touch (0) as TouchDown(). (A bit hacky.)
+  secondFingerDown.mTouches.AppendElement(SingleTouchData(0, ScreenIntPoint(10, 90), ScreenSize(0, 0), 0, 0));
+  secondFingerDown.mTouches.AppendElement(SingleTouchData(1, ScreenIntPoint(10, 80), ScreenSize(0, 0), 0, 0));
+  manager->ReceiveInputEvent(secondFingerDown, nullptr, nullptr);
+
+  // Release the fingers.
+  MultiTouchInput fingersUp = secondFingerDown;
+  fingersUp.mType = MultiTouchInput::MULTITOUCH_END;
+  manager->ReceiveInputEvent(fingersUp, nullptr, nullptr);
+
+  // Allow any animations to run their course.
+  child->AdvanceAnimationsUntilEnd();
+  rootApzc->AdvanceAnimationsUntilEnd();
+
+  // Make sure nothing is overscrolled.
+  EXPECT_FALSE(child->IsOverscrolled());
+  EXPECT_FALSE(rootApzc->IsOverscrolled());
+}
+
+// Test that flinging in a direction where one component of the fling goes into
+// overscroll but the other doesn't, results in just the one component being
+// handed off to the parent, while the original APZC continues flinging in the
+// other direction.
+TEST_F(APZScrollHandoffTester, PartialFlingHandoff) {
+  CreateScrollHandoffLayerTree1();
+
+  // Fling up and to the left. The child APZC has room to scroll up, but not
+  // to the left, so the horizontal component of the fling should be handed
+  // off to the parent APZC.
+  Pan(manager, ScreenIntPoint(90, 90), ScreenIntPoint(55, 55));
+
+  RefPtr<TestAsyncPanZoomController> parent = ApzcOf(root);
+  RefPtr<TestAsyncPanZoomController> child = ApzcOf(layers[1]);
+
+  // Advance the child's fling animation once to give the partial handoff
+  // a chance to occur.
+  mcc->AdvanceByMillis(10);
+  child->AdvanceAnimations(mcc->Time());
+
+  // Assert that partial handoff has occurred.
+  child->AssertStateIsFling();
+  parent->AssertStateIsFling();
+}
+
+// Here we test that if two flings are happening simultaneously, overscroll
+// is handed off correctly for each.
+TEST_F(APZScrollHandoffTester, SimultaneousFlings) {
+  SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
+
+  // Set up an initial APZC tree.
+  CreateScrollHandoffLayerTree3();
+
+  RefPtr<TestAsyncPanZoomController> parent1 = ApzcOf(layers[1]);
+  RefPtr<TestAsyncPanZoomController> child1 = ApzcOf(layers[2]);
+  RefPtr<TestAsyncPanZoomController> parent2 = ApzcOf(layers[3]);
+  RefPtr<TestAsyncPanZoomController> child2 = ApzcOf(layers[4]);
+
+  // Pan on the lower child.
+  Pan(child2, 45, 5);
+
+  // Pan on the upper child.
+  Pan(child1, 95, 55);
+
+  // Check that child1 and child2 are in a FLING state.
+  child1->AssertStateIsFling();
+  child2->AssertStateIsFling();
+
+  // Advance the animations on child1 and child2 until their end.
+  child1->AdvanceAnimationsUntilEnd();
+  child2->AdvanceAnimationsUntilEnd();
+
+  // Check that the flings have been handed off to the parents.
+  child1->AssertStateIsReset();
+  parent1->AssertStateIsFling();
+  child2->AssertStateIsReset();
+  parent2->AssertStateIsFling();
+}
+
+TEST_F(APZScrollHandoffTester, Scrollgrab) {
+  // Set up the layer tree
+  CreateScrollgrabLayerTree();
+
+  RefPtr<TestAsyncPanZoomController> childApzc = ApzcOf(layers[1]);
+
+  // Pan on the child, enough to fully scroll the scrollgrab parent (20 px)
+  // and leave some more (another 15 px) for the child.
+  Pan(childApzc, 80, 45);
+
+  // Check that the parent and child have scrolled as much as we expect.
+  EXPECT_EQ(20, rootApzc->GetFrameMetrics().GetScrollOffset().y);
+  EXPECT_EQ(15, childApzc->GetFrameMetrics().GetScrollOffset().y);
+}
+
+TEST_F(APZScrollHandoffTester, ScrollgrabFling) {
+  SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
+  // Set up the layer tree
+  CreateScrollgrabLayerTree();
+
+  RefPtr<TestAsyncPanZoomController> childApzc = ApzcOf(layers[1]);
+
+  // Pan on the child, not enough to fully scroll the scrollgrab parent.
+  Pan(childApzc, 80, 70);
+
+  // Check that it is the scrollgrab parent that's in a fling, not the child.
+  rootApzc->AssertStateIsFling();
+  childApzc->AssertStateIsReset();
+}
+
+TEST_F(APZScrollHandoffTester, ScrollgrabFlingAcceleration1) {
+  SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
+  CreateScrollgrabLayerTree(true /* make parent scrollable */);
+  TestFlingAcceleration();
+}
+
+TEST_F(APZScrollHandoffTester, ScrollgrabFlingAcceleration2) {
+  SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
+  CreateScrollgrabLayerTree(false /* do not make parent scrollable */);
+  TestFlingAcceleration();
+}
+
+TEST_F(APZScrollHandoffTester, ImmediateHandoffDisallowed_Pan) {
+  SCOPED_GFX_PREF(APZAllowImmediateHandoff, bool, false);
+
+  CreateScrollHandoffLayerTree1();
+
+  RefPtr<TestAsyncPanZoomController> parentApzc = ApzcOf(root);
+  RefPtr<TestAsyncPanZoomController> childApzc = ApzcOf(layers[1]);
+
+  // Pan on the child, enough to scroll it to its end and have scroll
+  // left to hand off. Since immediate handoff is disallowed, we expect
+  // the leftover scroll not to be handed off.
+  Pan(childApzc, 60, 5);
+
+  // Verify that the parent has not scrolled.
+  EXPECT_EQ(50, childApzc->GetFrameMetrics().GetScrollOffset().y);
+  EXPECT_EQ(0, parentApzc->GetFrameMetrics().GetScrollOffset().y);
+
+  // Pan again on the child. This time, since the child was scrolled to
+  // its end when the gesture began, we expect the scroll to be handed off.
+  Pan(childApzc, 60, 50);
+
+  // Verify that the parent scrolled.
+  EXPECT_EQ(10, parentApzc->GetFrameMetrics().GetScrollOffset().y);
+}
+
+TEST_F(APZScrollHandoffTester, ImmediateHandoffDisallowed_Fling) {
+  SCOPED_GFX_PREF(APZAllowImmediateHandoff, bool, false);
+  SCOPED_GFX_PREF(APZFlingMinVelocityThreshold, float, 0.0f);
+
+  CreateScrollHandoffLayerTree1();
+
+  RefPtr<TestAsyncPanZoomController> parentApzc = ApzcOf(root);
+  RefPtr<TestAsyncPanZoomController> childApzc = ApzcOf(layers[1]);
+
+  // Pan on the child, enough to get very close to the end, so that the
+  // subsequent fling reaches the end and has leftover velocity to hand off.
+  Pan(childApzc, 60, 12);
+
+  // Allow the fling to run its course.
+  childApzc->AdvanceAnimationsUntilEnd();
+  parentApzc->AdvanceAnimationsUntilEnd();
+
+  // Verify that the parent has not scrolled.
+  // The first comparison needs to be an ASSERT_NEAR because the fling
+  // computations are such that the final scroll position can be within
+  // COORDINATE_EPSILON of the end rather than right at the end.
+  ASSERT_NEAR(50, childApzc->GetFrameMetrics().GetScrollOffset().y, COORDINATE_EPSILON);
+  EXPECT_EQ(0, parentApzc->GetFrameMetrics().GetScrollOffset().y);
+
+  // Pan again on the child. This time, since the child was scrolled to
+  // its end when the gesture began, we expect the scroll to be handed off.
+  Pan(childApzc, 60, 50);
+
+  // Allow the fling to run its course. The fling should also be handed off.
+  childApzc->AdvanceAnimationsUntilEnd();
+  parentApzc->AdvanceAnimationsUntilEnd();
+
+  // Verify that the parent scrolled from the fling.
+  EXPECT_GT(parentApzc->GetFrameMetrics().GetScrollOffset().y, 10);
+}