Adding upstream version 115.7.0esr.upstream/115.7.0esr

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 639 insertions, 0 deletions

diff --git a/gfx/layers/apz/test/gtest/TestBasic.cpp b/gfx/layers/apz/test/gtest/TestBasic.cpp
new file mode 100644
index 0000000000..52cebfccd4
--- /dev/null
+++ b/gfx/layers/apz/test/gtest/TestBasic.cpp
@@ -0,0 +1,639 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 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 "APZCBasicTester.h"
+#include "APZTestCommon.h"
+
+#include "InputUtils.h"
+
+static ScrollGenerationCounter sGenerationCounter;
+
+TEST_F(APZCBasicTester, Overzoom) {
+  // the visible area of the document in CSS pixels is x=10 y=0 w=100 h=100
+  FrameMetrics fm;
+  fm.SetCompositionBounds(ParentLayerRect(0, 0, 100, 100));
+  fm.SetScrollableRect(CSSRect(0, 0, 125, 150));
+  fm.SetVisualScrollOffset(CSSPoint(10, 0));
+  fm.SetZoom(CSSToParentLayerScale(1.0));
+  fm.SetIsRootContent(true);
+  apzc->SetFrameMetrics(fm);
+
+  MakeApzcZoomable();
+
+  EXPECT_CALL(*mcc, RequestContentRepaint(_)).Times(1);
+
+  PinchWithPinchInputAndCheckStatus(apzc, ScreenIntPoint(50, 50), 0.5, true);
+
+  fm = apzc->GetFrameMetrics();
+  EXPECT_EQ(0.8f, fm.GetZoom().scale);
+  // bug 936721 - PGO builds introduce rounding error so
+  // use a fuzzy match instead
+  EXPECT_LT(std::abs(fm.GetVisualScrollOffset().x), 1e-5);
+  EXPECT_LT(std::abs(fm.GetVisualScrollOffset().y), 1e-5);
+}
+
+TEST_F(APZCBasicTester, ZoomLimits) {
+  SCOPED_GFX_PREF_FLOAT("apz.min_zoom", 0.9f);
+  SCOPED_GFX_PREF_FLOAT("apz.max_zoom", 2.0f);
+
+  // the visible area of the document in CSS pixels is x=10 y=0 w=100 h=100
+  FrameMetrics fm;
+  fm.SetCompositionBounds(ParentLayerRect(0, 0, 100, 100));
+  fm.SetScrollableRect(CSSRect(0, 0, 125, 150));
+  fm.SetZoom(CSSToParentLayerScale(1.0));
+  fm.SetIsRootContent(true);
+  apzc->SetFrameMetrics(fm);
+
+  MakeApzcZoomable();
+
+  // This should take the zoom scale to 0.8, but we've capped it at 0.9.
+  PinchWithPinchInputAndCheckStatus(apzc, ScreenIntPoint(50, 50), 0.5, true);
+
+  fm = apzc->GetFrameMetrics();
+  EXPECT_EQ(0.9f, fm.GetZoom().scale);
+
+  // This should take the zoom scale to 2.7, but we've capped it at 2.
+  PinchWithPinchInputAndCheckStatus(apzc, ScreenIntPoint(50, 50), 3, true);
+
+  fm = apzc->GetFrameMetrics();
+  EXPECT_EQ(2.0f, fm.GetZoom().scale);
+}
+
+TEST_F(APZCBasicTester, SimpleTransform) {
+  ParentLayerPoint pointOut;
+  AsyncTransform viewTransformOut;
+  apzc->SampleContentTransformForFrame(&viewTransformOut, pointOut);
+
+  EXPECT_EQ(ParentLayerPoint(), pointOut);
+  EXPECT_EQ(AsyncTransform(), viewTransformOut);
+}
+
+TEST_F(APZCBasicTester, ComplexTransform) {
+  // This test assumes there is a page that gets rendered to
+  // two layers. In CSS pixels, the first layer is 50x50 and
+  // the second layer is 25x50. The widget scale factor is 3.0
+  // and the presShell resolution is 2.0. Therefore, these layers
+  // end up being 300x300 and 150x300 in layer pixels.
+  //
+  // The second (child) layer has an additional CSS transform that
+  // stretches it by 2.0 on the x-axis. Therefore, after applying
+  // CSS transforms, the two layers are the same size in screen
+  // pixels.
+  //
+  // The screen itself is 24x24 in screen pixels (therefore 4x4 in
+  // CSS pixels). The displayport is 1 extra CSS pixel on all
+  // sides.
+
+  RefPtr<TestAsyncPanZoomController> childApzc =
+      new TestAsyncPanZoomController(LayersId{0}, mcc, tm);
+
+  const char* treeShape = "x(x)";
+  // LayerID                     0 1
+  LayerIntRegion layerVisibleRegion[] = {
+      LayerIntRect(0, 0, 300, 300),
+      LayerIntRect(0, 0, 150, 300),
+  };
+  Matrix4x4 transforms[] = {
+      Matrix4x4(),
+      Matrix4x4(),
+  };
+  transforms[0].PostScale(
+      0.5f, 0.5f,
+      1.0f);  // this results from the 2.0 resolution on the root layer
+  transforms[1].PostScale(
+      2.0f, 1.0f,
+      1.0f);  // this is the 2.0 x-axis CSS transform on the child layer
+
+  auto layers = TestWRScrollData::Create(treeShape, *updater,
+                                         layerVisibleRegion, transforms);
+
+  ScrollMetadata metadata;
+  FrameMetrics& metrics = metadata.GetMetrics();
+  metrics.SetCompositionBounds(ParentLayerRect(0, 0, 24, 24));
+  metrics.SetDisplayPort(CSSRect(-1, -1, 6, 6));
+  metrics.SetVisualScrollOffset(CSSPoint(10, 10));
+  metrics.SetLayoutViewport(CSSRect(10, 10, 8, 8));
+  metrics.SetScrollableRect(CSSRect(0, 0, 50, 50));
+  metrics.SetCumulativeResolution(LayoutDeviceToLayerScale(2));
+  metrics.SetPresShellResolution(2.0f);
+  metrics.SetZoom(CSSToParentLayerScale(6));
+  metrics.SetDevPixelsPerCSSPixel(CSSToLayoutDeviceScale(3));
+  metrics.SetScrollId(ScrollableLayerGuid::START_SCROLL_ID);
+
+  ScrollMetadata childMetadata = metadata;
+  FrameMetrics& childMetrics = childMetadata.GetMetrics();
+  childMetrics.SetScrollId(ScrollableLayerGuid::START_SCROLL_ID + 1);
+
+  layers[0]->AppendScrollMetadata(layers, metadata);
+  layers[1]->AppendScrollMetadata(layers, childMetadata);
+
+  ParentLayerPoint pointOut;
+  AsyncTransform viewTransformOut;
+
+  // Both the parent and child layer should behave exactly the same here,
+  // because the CSS transform on the child layer does not affect the
+  // SampleContentTransformForFrame code
+
+  // initial transform
+  apzc->SetFrameMetrics(metrics);
+  apzc->NotifyLayersUpdated(metadata, true, true);
+  apzc->SampleContentTransformForFrame(&viewTransformOut, pointOut);
+  EXPECT_EQ(AsyncTransform(LayerToParentLayerScale(1), ParentLayerPoint()),
+            viewTransformOut);
+  EXPECT_EQ(ParentLayerPoint(60, 60), pointOut);
+
+  childApzc->SetFrameMetrics(childMetrics);
+  childApzc->NotifyLayersUpdated(childMetadata, true, true);
+  childApzc->SampleContentTransformForFrame(&viewTransformOut, pointOut);
+  EXPECT_EQ(AsyncTransform(LayerToParentLayerScale(1), ParentLayerPoint()),
+            viewTransformOut);
+  EXPECT_EQ(ParentLayerPoint(60, 60), pointOut);
+
+  // do an async scroll by 5 pixels and check the transform
+  metrics.ScrollBy(CSSPoint(5, 0));
+  apzc->SetFrameMetrics(metrics);
+  apzc->SampleContentTransformForFrame(&viewTransformOut, pointOut);
+  EXPECT_EQ(
+      AsyncTransform(LayerToParentLayerScale(1), ParentLayerPoint(-30, 0)),
+      viewTransformOut);
+  EXPECT_EQ(ParentLayerPoint(90, 60), pointOut);
+
+  childMetrics.ScrollBy(CSSPoint(5, 0));
+  childApzc->SetFrameMetrics(childMetrics);
+  childApzc->SampleContentTransformForFrame(&viewTransformOut, pointOut);
+  EXPECT_EQ(
+      AsyncTransform(LayerToParentLayerScale(1), ParentLayerPoint(-30, 0)),
+      viewTransformOut);
+  EXPECT_EQ(ParentLayerPoint(90, 60), pointOut);
+
+  // do an async zoom of 1.5x and check the transform
+  metrics.ZoomBy(1.5f);
+  apzc->SetFrameMetrics(metrics);
+  apzc->SampleContentTransformForFrame(&viewTransformOut, pointOut);
+  EXPECT_EQ(
+      AsyncTransform(LayerToParentLayerScale(1.5), ParentLayerPoint(-45, 0)),
+      viewTransformOut);
+  EXPECT_EQ(ParentLayerPoint(135, 90), pointOut);
+
+  childMetrics.ZoomBy(1.5f);
+  childApzc->SetFrameMetrics(childMetrics);
+  childApzc->SampleContentTransformForFrame(&viewTransformOut, pointOut);
+  EXPECT_EQ(
+      AsyncTransform(LayerToParentLayerScale(1.5), ParentLayerPoint(-45, 0)),
+      viewTransformOut);
+  EXPECT_EQ(ParentLayerPoint(135, 90), pointOut);
+
+  childApzc->Destroy();
+}
+
+TEST_F(APZCBasicTester, Fling) {
+  SCOPED_GFX_PREF_FLOAT("apz.fling_min_velocity_threshold", 0.0f);
+  int touchStart = 50;
+  int touchEnd = 10;
+  ParentLayerPoint pointOut;
+  AsyncTransform viewTransformOut;
+
+  // Fling down. Each step scroll further down
+  Pan(apzc, touchStart, touchEnd);
+  ParentLayerPoint lastPoint;
+  for (int i = 1; i < 50; i += 1) {
+    apzc->SampleContentTransformForFrame(&viewTransformOut, pointOut,
+                                         TimeDuration::FromMilliseconds(1));
+    EXPECT_GT(pointOut.y, lastPoint.y);
+    lastPoint = pointOut;
+  }
+}
+
+#ifndef MOZ_WIDGET_ANDROID  // Maybe fails on Android
+TEST_F(APZCBasicTester, ResumeInterruptedTouchDrag_Bug1592435) {
+  // Start a touch-drag and scroll some amount, not lifting the finger.
+  SCOPED_GFX_PREF_FLOAT("apz.touch_start_tolerance", 1.0f / 1000.0f);
+  ScreenIntPoint touchPos(10, 50);
+  uint64_t touchBlock = TouchDown(apzc, touchPos, mcc->Time()).mInputBlockId;
+  SetDefaultAllowedTouchBehavior(apzc, touchBlock);
+  for (int i = 0; i < 20; ++i) {
+    touchPos.y -= 1;
+    mcc->AdvanceByMillis(1);
+    TouchMove(apzc, touchPos, mcc->Time());
+  }
+
+  // Take note of the scroll offset before the interruption.
+  CSSPoint scrollOffsetBeforeInterruption =
+      apzc->GetFrameMetrics().GetVisualScrollOffset();
+
+  // Have the main thread interrupt the touch-drag by sending
+  // a main thread scroll update to a nearby location.
+  CSSPoint mainThreadOffset = scrollOffsetBeforeInterruption;
+  mainThreadOffset.y -= 5;
+  ScrollMetadata metadata = apzc->GetScrollMetadata();
+  metadata.GetMetrics().SetLayoutScrollOffset(mainThreadOffset);
+  nsTArray<ScrollPositionUpdate> scrollUpdates;
+  scrollUpdates.AppendElement(ScrollPositionUpdate::NewScroll(
+      ScrollOrigin::Other, CSSPoint::ToAppUnits(mainThreadOffset)));
+  metadata.SetScrollUpdates(scrollUpdates);
+  metadata.GetMetrics().SetScrollGeneration(
+      scrollUpdates.LastElement().GetGeneration());
+  apzc->NotifyLayersUpdated(metadata, false, true);
+
+  // Continue and finish the touch-drag gesture.
+  for (int i = 0; i < 20; ++i) {
+    touchPos.y -= 1;
+    mcc->AdvanceByMillis(1);
+    TouchMove(apzc, touchPos, mcc->Time());
+  }
+
+  // Check that the portion of the touch-drag that occurred after
+  // the interruption caused additional scrolling.
+  CSSPoint finalScrollOffset = apzc->GetFrameMetrics().GetVisualScrollOffset();
+  EXPECT_GT(finalScrollOffset.y, scrollOffsetBeforeInterruption.y);
+
+  // Now do the same thing, but for a visual scroll update.
+  scrollOffsetBeforeInterruption =
+      apzc->GetFrameMetrics().GetVisualScrollOffset();
+  mainThreadOffset = scrollOffsetBeforeInterruption;
+  mainThreadOffset.y -= 5;
+  metadata = apzc->GetScrollMetadata();
+  metadata.GetMetrics().SetVisualDestination(mainThreadOffset);
+  metadata.GetMetrics().SetScrollGeneration(
+      sGenerationCounter.NewMainThreadGeneration());
+  metadata.GetMetrics().SetVisualScrollUpdateType(FrameMetrics::eMainThread);
+  scrollUpdates.Clear();
+  metadata.SetScrollUpdates(scrollUpdates);
+  apzc->NotifyLayersUpdated(metadata, false, true);
+  for (int i = 0; i < 20; ++i) {
+    touchPos.y -= 1;
+    mcc->AdvanceByMillis(1);
+    TouchMove(apzc, touchPos, mcc->Time());
+  }
+  finalScrollOffset = apzc->GetFrameMetrics().GetVisualScrollOffset();
+  EXPECT_GT(finalScrollOffset.y, scrollOffsetBeforeInterruption.y);
+
+  // Clean up by ending the touch gesture.
+  mcc->AdvanceByMillis(1);
+  TouchUp(apzc, touchPos, mcc->Time());
+}
+#endif
+
+TEST_F(APZCBasicTester, RelativeScrollOffset) {
+  // Set up initial conditions: zoomed in, layout offset at (100, 100),
+  // visual offset at (120, 120); the relative offset is therefore (20, 20).
+  ScrollMetadata metadata;
+  FrameMetrics& metrics = metadata.GetMetrics();
+  metrics.SetScrollableRect(CSSRect(0, 0, 1000, 1000));
+  metrics.SetLayoutViewport(CSSRect(100, 100, 100, 100));
+  metrics.SetZoom(CSSToParentLayerScale(2.0));
+  metrics.SetCompositionBounds(ParentLayerRect(0, 0, 100, 100));
+  metrics.SetVisualScrollOffset(CSSPoint(120, 120));
+  metrics.SetIsRootContent(true);
+  apzc->SetFrameMetrics(metrics);
+
+  // Scroll the layout viewport to (200, 200).
+  ScrollMetadata mainThreadMetadata = metadata;
+  FrameMetrics& mainThreadMetrics = mainThreadMetadata.GetMetrics();
+  mainThreadMetrics.SetLayoutScrollOffset(CSSPoint(200, 200));
+  nsTArray<ScrollPositionUpdate> scrollUpdates;
+  scrollUpdates.AppendElement(ScrollPositionUpdate::NewScroll(
+      ScrollOrigin::Other, CSSPoint::ToAppUnits(CSSPoint(200, 200))));
+  mainThreadMetadata.SetScrollUpdates(scrollUpdates);
+  mainThreadMetrics.SetScrollGeneration(
+      scrollUpdates.LastElement().GetGeneration());
+  apzc->NotifyLayersUpdated(mainThreadMetadata, /*isFirstPaint=*/false,
+                            /*thisLayerTreeUpdated=*/true);
+
+  // Check that the relative offset has been preserved.
+  metrics = apzc->GetFrameMetrics();
+  EXPECT_EQ(metrics.GetLayoutScrollOffset(), CSSPoint(200, 200));
+  EXPECT_EQ(metrics.GetVisualScrollOffset(), CSSPoint(220, 220));
+}
+
+TEST_F(APZCBasicTester, MultipleSmoothScrollsSmooth) {
+  SCOPED_GFX_PREF_BOOL("general.smoothScroll", true);
+  // We want to test that if we send multiple smooth scroll requests that we
+  // still smoothly animate, ie that we get non-zero change every frame while
+  // the animation is running.
+
+  ScrollMetadata metadata;
+  FrameMetrics& metrics = metadata.GetMetrics();
+  metrics.SetScrollableRect(CSSRect(0, 0, 100, 10000));
+  metrics.SetLayoutViewport(CSSRect(0, 0, 100, 100));
+  metrics.SetZoom(CSSToParentLayerScale(1.0));
+  metrics.SetCompositionBounds(ParentLayerRect(0, 0, 100, 100));
+  metrics.SetVisualScrollOffset(CSSPoint(0, 0));
+  metrics.SetIsRootContent(true);
+  apzc->SetFrameMetrics(metrics);
+
+  // Structure of this test.
+  //   -send a pure relative smooth scroll request via NotifyLayersUpdated
+  //   -advance animations a few times, check that scroll offset is increasing
+  //    after the first few advances
+  //   -send a pure relative smooth scroll request via NotifyLayersUpdated
+  //   -advance animations a few times, check that scroll offset is increasing
+  //   -send a pure relative smooth scroll request via NotifyLayersUpdated
+  //   -advance animations a few times, check that scroll offset is increasing
+
+  ScrollMetadata metadata2 = metadata;
+  nsTArray<ScrollPositionUpdate> scrollUpdates2;
+  scrollUpdates2.AppendElement(ScrollPositionUpdate::NewPureRelativeScroll(
+      ScrollOrigin::Other, ScrollMode::Smooth,
+      CSSPoint::ToAppUnits(CSSPoint(0, 200))));
+  metadata2.SetScrollUpdates(scrollUpdates2);
+  metadata2.GetMetrics().SetScrollGeneration(
+      scrollUpdates2.LastElement().GetGeneration());
+  apzc->NotifyLayersUpdated(metadata2, /*isFirstPaint=*/false,
+                            /*thisLayerTreeUpdated=*/true);
+
+  // Get the animation going
+  for (uint32_t i = 0; i < 3; i++) {
+    SampleAnimationOneFrame();
+  }
+
+  float offset =
+      apzc->GetCurrentAsyncScrollOffset(AsyncPanZoomController::eForCompositing)
+          .y;
+  ASSERT_GT(offset, 0);
+  float lastOffset = offset;
+
+  for (uint32_t i = 0; i < 2; i++) {
+    for (uint32_t j = 0; j < 3; j++) {
+      SampleAnimationOneFrame();
+      offset = apzc->GetCurrentAsyncScrollOffset(
+                       AsyncPanZoomController::eForCompositing)
+                   .y;
+      ASSERT_GT(offset, lastOffset);
+      lastOffset = offset;
+    }
+
+    ScrollMetadata metadata3 = metadata;
+    nsTArray<ScrollPositionUpdate> scrollUpdates3;
+    scrollUpdates3.AppendElement(ScrollPositionUpdate::NewPureRelativeScroll(
+        ScrollOrigin::Other, ScrollMode::Smooth,
+        CSSPoint::ToAppUnits(CSSPoint(0, 200))));
+    metadata3.SetScrollUpdates(scrollUpdates3);
+    metadata3.GetMetrics().SetScrollGeneration(
+        scrollUpdates3.LastElement().GetGeneration());
+    apzc->NotifyLayersUpdated(metadata3, /*isFirstPaint=*/false,
+                              /*thisLayerTreeUpdated=*/true);
+  }
+
+  for (uint32_t j = 0; j < 7; j++) {
+    SampleAnimationOneFrame();
+    offset = apzc->GetCurrentAsyncScrollOffset(
+                     AsyncPanZoomController::eForCompositing)
+                 .y;
+    ASSERT_GT(offset, lastOffset);
+    lastOffset = offset;
+  }
+}
+
+class APZCSmoothScrollTester : public APZCBasicTester {
+ public:
+  // Test that a smooth scroll animation correctly handles its destination
+  // being updated by a relative scroll delta.
+  void TestSmoothScrollDestinationUpdate() {
+    // Set up scroll frame. Starting scroll position is (0, 0).
+    ScrollMetadata metadata;
+    FrameMetrics& metrics = metadata.GetMetrics();
+    metrics.SetScrollableRect(CSSRect(0, 0, 100, 10000));
+    metrics.SetLayoutViewport(CSSRect(0, 0, 100, 100));
+    metrics.SetZoom(CSSToParentLayerScale(1.0));
+    metrics.SetCompositionBounds(ParentLayerRect(0, 0, 100, 100));
+    metrics.SetVisualScrollOffset(CSSPoint(0, 0));
+    metrics.SetIsRootContent(true);
+    apzc->SetFrameMetrics(metrics);
+
+    // Start smooth scroll via main-thread request.
+    nsTArray<ScrollPositionUpdate> scrollUpdates;
+    scrollUpdates.AppendElement(ScrollPositionUpdate::NewPureRelativeScroll(
+        ScrollOrigin::Other, ScrollMode::Smooth,
+        CSSPoint::ToAppUnits(CSSPoint(0, 1000))));
+    metadata.SetScrollUpdates(scrollUpdates);
+    metrics.SetScrollGeneration(scrollUpdates.LastElement().GetGeneration());
+    apzc->NotifyLayersUpdated(metadata, false, true);
+
+    // Sample the smooth scroll animation until we get past y=500.
+    apzc->AssertStateIsSmoothScroll();
+    float y = 0;
+    while (y < 500) {
+      SampleAnimationOneFrame();
+      y = apzc->GetFrameMetrics().GetVisualScrollOffset().y;
+    }
+
+    // Send a relative scroll of y = -400.
+    scrollUpdates.Clear();
+    scrollUpdates.AppendElement(ScrollPositionUpdate::NewRelativeScroll(
+        CSSPoint::ToAppUnits(CSSPoint(0, 500)),
+        CSSPoint::ToAppUnits(CSSPoint(0, 100))));
+    metadata.SetScrollUpdates(scrollUpdates);
+    metrics.SetScrollGeneration(scrollUpdates.LastElement().GetGeneration());
+    apzc->NotifyLayersUpdated(metadata, false, false);
+
+    // Verify the relative scroll was applied but didn't cancel the animation.
+    float y2 = apzc->GetFrameMetrics().GetVisualScrollOffset().y;
+    ASSERT_EQ(y2, y - 400);
+    apzc->AssertStateIsSmoothScroll();
+
+    // Sample the animation again and check that it respected the relative
+    // scroll.
+    SampleAnimationOneFrame();
+    float y3 = apzc->GetFrameMetrics().GetVisualScrollOffset().y;
+    ASSERT_GT(y3, y2);
+    ASSERT_LT(y3, 500);
+
+    // Continue animation until done and check that it ended up at a correctly
+    // adjusted destination.
+    apzc->AdvanceAnimationsUntilEnd();
+    float y4 = apzc->GetFrameMetrics().GetVisualScrollOffset().y;
+    ASSERT_EQ(y4, 600);  // 1000 (initial destination) - 400 (relative scroll)
+  }
+};
+
+TEST_F(APZCSmoothScrollTester, SmoothScrollDestinationUpdateBezier) {
+  SCOPED_GFX_PREF_BOOL("general.smoothScroll", true);
+  SCOPED_GFX_PREF_BOOL("general.smoothScroll.msdPhysics.enabled", false);
+  TestSmoothScrollDestinationUpdate();
+}
+
+TEST_F(APZCSmoothScrollTester, SmoothScrollDestinationUpdateMsd) {
+  SCOPED_GFX_PREF_BOOL("general.smoothScroll", true);
+  SCOPED_GFX_PREF_BOOL("general.smoothScroll.msdPhysics.enabled", true);
+  TestSmoothScrollDestinationUpdate();
+}
+
+TEST_F(APZCBasicTester, ZoomAndScrollableRectChangeAfterZoomChange) {
+  // We want to check that a small scrollable rect change (which causes us to
+  // reclamp our scroll position, including in the sampled state) does not move
+  // the scroll offset in the sample state based the zoom in the apzc, only
+  // based on the zoom in the sampled state.
+
+  // First we zoom in to the right hand side. Then start zooming out, then send
+  // a scrollable rect change and check that it doesn't change the sampled state
+  // scroll offset.
+
+  ScrollMetadata metadata;
+  FrameMetrics& metrics = metadata.GetMetrics();
+  metrics.SetCompositionBounds(ParentLayerRect(0, 0, 100, 100));
+  metrics.SetScrollableRect(CSSRect(0, 0, 100, 1000));
+  metrics.SetLayoutViewport(CSSRect(0, 0, 100, 100));
+  metrics.SetVisualScrollOffset(CSSPoint(0, 0));
+  metrics.SetZoom(CSSToParentLayerScale(1.0));
+  metrics.SetIsRootContent(true);
+  apzc->SetFrameMetrics(metrics);
+
+  MakeApzcZoomable();
+
+  // Zoom to right side.
+  ZoomTarget zoomTarget{CSSRect(75, 25, 25, 25)};
+  apzc->ZoomToRect(zoomTarget, 0);
+
+  // Run the animation to completion, should take 250ms/16.67ms = 15 frames, but
+  // do extra to make sure.
+  for (uint32_t i = 0; i < 30; i++) {
+    SampleAnimationOneFrame();
+  }
+
+  EXPECT_FALSE(apzc->IsAsyncZooming());
+
+  // Zoom out.
+  ZoomTarget zoomTarget2{CSSRect(0, 0, 100, 100)};
+  apzc->ZoomToRect(zoomTarget2, 0);
+
+  // Run the animation a few times to get it going.
+  for (uint32_t i = 0; i < 2; i++) {
+    SampleAnimationOneFrame();
+  }
+
+  // Check that it is decreasing in scale.
+  float prevScale =
+      apzc->GetCurrentPinchZoomScale(AsyncPanZoomController::eForCompositing)
+          .scale;
+  for (uint32_t i = 0; i < 2; i++) {
+    SampleAnimationOneFrame();
+    float scale =
+        apzc->GetCurrentPinchZoomScale(AsyncPanZoomController::eForCompositing)
+            .scale;
+    ASSERT_GT(prevScale, scale);
+    prevScale = scale;
+  }
+
+  float offset =
+      apzc->GetCurrentAsyncScrollOffset(AsyncPanZoomController::eForCompositing)
+          .x;
+
+  // Change the scrollable rect slightly to trigger a reclamp.
+  ScrollMetadata metadata2 = metadata;
+  metadata2.GetMetrics().SetScrollableRect(CSSRect(0, 0, 100, 1000.2));
+  apzc->NotifyLayersUpdated(metadata2, /*isFirstPaint=*/false,
+                            /*thisLayerTreeUpdated=*/true);
+
+  float newOffset =
+      apzc->GetCurrentAsyncScrollOffset(AsyncPanZoomController::eForCompositing)
+          .x;
+
+  ASSERT_EQ(newOffset, offset);
+}
+
+TEST_F(APZCBasicTester, ZoomToRectAndCompositionBoundsChange) {
+  // We want to check that content sending a composition bounds change (due to
+  // addition of scrollbars) during a zoom animation does not cause us to take
+  // the out of date content resolution.
+
+  ScrollMetadata metadata;
+  FrameMetrics& metrics = metadata.GetMetrics();
+  metrics.SetCompositionBounds(ParentLayerRect(0, 0, 100, 100));
+  metrics.SetCompositionBoundsWidthIgnoringScrollbars(ParentLayerCoord{100});
+  metrics.SetScrollableRect(CSSRect(0, 0, 100, 1000));
+  metrics.SetLayoutViewport(CSSRect(0, 0, 100, 100));
+  metrics.SetVisualScrollOffset(CSSPoint(0, 0));
+  metrics.SetZoom(CSSToParentLayerScale(1.0));
+  metrics.SetIsRootContent(true);
+  apzc->SetFrameMetrics(metrics);
+
+  MakeApzcZoomable();
+
+  // Start a zoom to a rect.
+  ZoomTarget zoomTarget{CSSRect(25, 25, 25, 25)};
+  apzc->ZoomToRect(zoomTarget, 0);
+
+  // Run the animation a few times to get it going.
+  // Check that it is increasing in scale.
+  float prevScale =
+      apzc->GetCurrentPinchZoomScale(AsyncPanZoomController::eForCompositing)
+          .scale;
+  for (uint32_t i = 0; i < 3; i++) {
+    SampleAnimationOneFrame();
+    float scale =
+        apzc->GetCurrentPinchZoomScale(AsyncPanZoomController::eForCompositing)
+            .scale;
+    ASSERT_GE(scale, prevScale);
+    prevScale = scale;
+  }
+
+  EXPECT_TRUE(apzc->IsAsyncZooming());
+
+  // Simulate the appearance of a scrollbar by reducing the width of
+  // the composition bounds, while keeping
+  // mCompositionBoundsWidthIgnoringScrollbars unchanged.
+  ScrollMetadata metadata2 = metadata;
+  metadata2.GetMetrics().SetCompositionBounds(ParentLayerRect(0, 0, 90, 100));
+  apzc->NotifyLayersUpdated(metadata2, /*isFirstPaint=*/false,
+                            /*thisLayerTreeUpdated=*/true);
+
+  float scale =
+      apzc->GetCurrentPinchZoomScale(AsyncPanZoomController::eForCompositing)
+          .scale;
+
+  ASSERT_EQ(scale, prevScale);
+
+  // Run the rest of the animation to completion, should take 250ms/16.67ms = 15
+  // frames total, but do extra to make sure.
+  for (uint32_t i = 0; i < 30; i++) {
+    SampleAnimationOneFrame();
+    scale =
+        apzc->GetCurrentPinchZoomScale(AsyncPanZoomController::eForCompositing)
+            .scale;
+    ASSERT_GE(scale, prevScale);
+    prevScale = scale;
+  }
+
+  EXPECT_FALSE(apzc->IsAsyncZooming());
+}
+
+TEST_F(APZCBasicTester, StartTolerance) {
+  SCOPED_GFX_PREF_FLOAT("apz.touch_start_tolerance", 10 / tm->GetDPI());
+
+  FrameMetrics fm;
+  fm.SetCompositionBounds(ParentLayerRect(0, 0, 100, 100));
+  fm.SetScrollableRect(CSSRect(0, 0, 100, 300));
+  fm.SetVisualScrollOffset(CSSPoint(0, 50));
+  fm.SetIsRootContent(true);
+  apzc->SetFrameMetrics(fm);
+
+  uint64_t touchBlock = TouchDown(apzc, {50, 50}, mcc->Time()).mInputBlockId;
+  SetDefaultAllowedTouchBehavior(apzc, touchBlock);
+
+  CSSPoint initialScrollOffset =
+      apzc->GetFrameMetrics().GetVisualScrollOffset();
+
+  mcc->AdvanceByMillis(1);
+  TouchMove(apzc, {50, 70}, mcc->Time());
+
+  // Expect 10 pixels of scrolling: the distance from (50,50) to (50,70)
+  // minus the 10-pixel touch start tolerance.
+  ASSERT_EQ(initialScrollOffset.y - 10,
+            apzc->GetFrameMetrics().GetVisualScrollOffset().y);
+
+  mcc->AdvanceByMillis(1);
+  TouchMove(apzc, {50, 90}, mcc->Time());
+
+  // Expect 30 pixels of scrolling: the distance from (50,50) to (50,90)
+  // minus the 10-pixel touch start tolerance.
+  ASSERT_EQ(initialScrollOffset.y - 30,
+            apzc->GetFrameMetrics().GetVisualScrollOffset().y);
+
+  // Clean up by ending the touch gesture.
+  mcc->AdvanceByMillis(1);
+  TouchUp(apzc, {50, 90}, mcc->Time());
+}