cc/CCDamageTrackerTest.cpp

// Copyright 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "config.h"

#include "CCDamageTracker.h"

#include "CCGeometryTestUtils.h"
#include "CCLayerImpl.h"
#include "CCLayerSorter.h"
#include "CCLayerTreeHostCommon.h"
#include "CCMathUtil.h"
#include "CCSingleThreadProxy.h"
#include "testing/gtest/include/gtest/gtest.h"
#include <public/WebFilterOperation.h>
#include <public/WebFilterOperations.h>

using namespace cc;
using namespace WebKit;
using namespace WTF;
using namespace WebKitTests;

namespace {

void executeCalculateDrawTransformsAndVisibility(CCLayerImpl* root, std::vector<CCLayerImpl*>& renderSurfaceLayerList)
{
    CCLayerSorter layerSorter;
    int dummyMaxTextureSize = 512;

    // Sanity check: The test itself should create the root layer's render surface, so
    //               that the surface (and its damage tracker) can persist across multiple
    //               calls to this function.
    ASSERT_TRUE(root->renderSurface());
    ASSERT_FALSE(renderSurfaceLayerList.size());

    CCLayerTreeHostCommon::calculateDrawTransforms(root, root->bounds(), 1, 1, &layerSorter, dummyMaxTextureSize, renderSurfaceLayerList);
}

void clearDamageForAllSurfaces(CCLayerImpl* layer)
{
    if (layer->renderSurface())
        layer->renderSurface()->damageTracker()->didDrawDamagedArea();

    // Recursively clear damage for any existing surface.
    for (size_t i = 0; i < layer->children().size(); ++i)
        clearDamageForAllSurfaces(layer->children()[i]);
}

void emulateDrawingOneFrame(CCLayerImpl* root)
{
    // This emulates only the steps that are relevant to testing the damage tracker:
    //   1. computing the render passes and layerlists
    //   2. updating all damage trackers in the correct order
    //   3. resetting all updateRects and propertyChanged flags for all layers and surfaces.

    std::vector<CCLayerImpl*> renderSurfaceLayerList;
    executeCalculateDrawTransformsAndVisibility(root, renderSurfaceLayerList);

    // Iterate back-to-front, so that damage correctly propagates from descendant surfaces to ancestors.
    for (int i = renderSurfaceLayerList.size() - 1; i >= 0; --i) {
        CCRenderSurface* targetSurface = renderSurfaceLayerList[i]->renderSurface();
        targetSurface->damageTracker()->updateDamageTrackingState(targetSurface->layerList(), targetSurface->owningLayerId(), targetSurface->surfacePropertyChangedOnlyFromDescendant(), targetSurface->contentRect(), renderSurfaceLayerList[i]->maskLayer(), renderSurfaceLayerList[i]->filters());
    }

    root->resetAllChangeTrackingForSubtree();
}

PassOwnPtr<CCLayerImpl> createTestTreeWithOneSurface()
{
    OwnPtr<CCLayerImpl> root = CCLayerImpl::create(1);
    OwnPtr<CCLayerImpl> child = CCLayerImpl::create(2);

    root->setPosition(FloatPoint::zero());
    root->setAnchorPoint(FloatPoint::zero());
    root->setBounds(IntSize(500, 500));
    root->setContentBounds(IntSize(500, 500));
    root->setDrawsContent(true);
    root->createRenderSurface();
    root->renderSurface()->setContentRect(IntRect(IntPoint(), IntSize(500, 500)));

    child->setPosition(FloatPoint(100, 100));
    child->setAnchorPoint(FloatPoint::zero());
    child->setBounds(IntSize(30, 30));
    child->setContentBounds(IntSize(30, 30));
    child->setDrawsContent(true);
    root->addChild(child.release());

    return root.release();
}

PassOwnPtr<CCLayerImpl> createTestTreeWithTwoSurfaces()
{
    // This test tree has two render surfaces: one for the root, and one for
    // child1. Additionally, the root has a second child layer, and child1 has two
    // children of its own.

    OwnPtr<CCLayerImpl> root = CCLayerImpl::create(1);
    OwnPtr<CCLayerImpl> child1 = CCLayerImpl::create(2);
    OwnPtr<CCLayerImpl> child2 = CCLayerImpl::create(3);
    OwnPtr<CCLayerImpl> grandChild1 = CCLayerImpl::create(4);
    OwnPtr<CCLayerImpl> grandChild2 = CCLayerImpl::create(5);

    root->setPosition(FloatPoint::zero());
    root->setAnchorPoint(FloatPoint::zero());
    root->setBounds(IntSize(500, 500));
    root->setContentBounds(IntSize(500, 500));
    root->setDrawsContent(true);
    root->createRenderSurface();
    root->renderSurface()->setContentRect(IntRect(IntPoint(), IntSize(500, 500)));

    child1->setPosition(FloatPoint(100, 100));
    child1->setAnchorPoint(FloatPoint::zero());
    child1->setBounds(IntSize(30, 30));
    child1->setContentBounds(IntSize(30, 30));
    child1->setOpacity(0.5); // with a child that drawsContent, this will cause the layer to create its own renderSurface.
    child1->setDrawsContent(false); // this layer does not draw, but is intended to create its own renderSurface.

    child2->setPosition(FloatPoint(11, 11));
    child2->setAnchorPoint(FloatPoint::zero());
    child2->setBounds(IntSize(18, 18));
    child2->setContentBounds(IntSize(18, 18));
    child2->setDrawsContent(true);

    grandChild1->setPosition(FloatPoint(200, 200));
    grandChild1->setAnchorPoint(FloatPoint::zero());
    grandChild1->setBounds(IntSize(6, 8));
    grandChild1->setContentBounds(IntSize(6, 8));
    grandChild1->setDrawsContent(true);

    grandChild2->setPosition(FloatPoint(190, 190));
    grandChild2->setAnchorPoint(FloatPoint::zero());
    grandChild2->setBounds(IntSize(6, 8));
    grandChild2->setContentBounds(IntSize(6, 8));
    grandChild2->setDrawsContent(true);

    child1->addChild(grandChild1.release());
    child1->addChild(grandChild2.release());
    root->addChild(child1.release());
    root->addChild(child2.release());

    return root.release();
}

PassOwnPtr<CCLayerImpl> createAndSetUpTestTreeWithOneSurface()
{
    OwnPtr<CCLayerImpl> root = createTestTreeWithOneSurface();

    // Setup includes going past the first frame which always damages everything, so
    // that we can actually perform specific tests.
    emulateDrawingOneFrame(root.get());

    return root.release();
}

PassOwnPtr<CCLayerImpl> createAndSetUpTestTreeWithTwoSurfaces()
{
    OwnPtr<CCLayerImpl> root = createTestTreeWithTwoSurfaces();

    // Setup includes going past the first frame which always damages everything, so
    // that we can actually perform specific tests.
    emulateDrawingOneFrame(root.get());

    return root.release();
}

class CCDamageTrackerTest : public testing::Test {
private:
    // For testing purposes, fake that we are on the impl thread.
    DebugScopedSetImplThread setImplThread;
};

TEST_F(CCDamageTrackerTest, sanityCheckTestTreeWithOneSurface)
{
    // Sanity check that the simple test tree will actually produce the expected render
    // surfaces and layer lists.

    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();

    EXPECT_EQ(2u, root->renderSurface()->layerList().size());
    EXPECT_EQ(1, root->renderSurface()->layerList()[0]->id());
    EXPECT_EQ(2, root->renderSurface()->layerList()[1]->id());

    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 500, 500), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, sanityCheckTestTreeWithTwoSurfaces)
{
    // Sanity check that the complex test tree will actually produce the expected render
    // surfaces and layer lists.

    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();

    CCLayerImpl* child1 = root->children()[0];
    CCLayerImpl* child2 = root->children()[1];
    FloatRect childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();

    ASSERT_TRUE(child1->renderSurface());
    EXPECT_FALSE(child2->renderSurface());
    EXPECT_EQ(3u, root->renderSurface()->layerList().size());
    EXPECT_EQ(2u, child1->renderSurface()->layerList().size());

    // The render surface for child1 only has a contentRect that encloses grandChild1 and grandChild2, because child1 does not draw content.
    EXPECT_FLOAT_RECT_EQ(FloatRect(190, 190, 16, 18), childDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 500, 500), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForUpdateRects)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child = root->children()[0];

    // CASE 1: Setting the update rect should cause the corresponding damage to the surface.
    //
    clearDamageForAllSurfaces(root.get());
    child->setUpdateRect(FloatRect(10, 11, 12, 13));
    emulateDrawingOneFrame(root.get());

    // Damage position on the surface should be: position of updateRect (10, 11) relative to the child (100, 100).
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(110, 111, 12, 13), rootDamageRect);

    // CASE 2: The same update rect twice in a row still produces the same damage.
    //
    clearDamageForAllSurfaces(root.get());
    child->setUpdateRect(FloatRect(10, 11, 12, 13));
    emulateDrawingOneFrame(root.get());
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(110, 111, 12, 13), rootDamageRect);

    // CASE 3: Setting a different update rect should cause damage on the new update region, but no additional exposed old region.
    //
    clearDamageForAllSurfaces(root.get());
    child->setUpdateRect(FloatRect(20, 25, 1, 2));
    emulateDrawingOneFrame(root.get());

    // Damage position on the surface should be: position of updateRect (20, 25) relative to the child (100, 100).
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(120, 125, 1, 2), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForPropertyChanges)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child = root->children()[0];

    // CASE 1: The layer's property changed flag takes priority over update rect.
    //
    clearDamageForAllSurfaces(root.get());
    child->setUpdateRect(FloatRect(10, 11, 12, 13));
    child->setOpacity(0.5);
    emulateDrawingOneFrame(root.get());

    // Sanity check - we should not have accidentally created a separate render surface for the translucent layer.
    ASSERT_FALSE(child->renderSurface());
    ASSERT_EQ(2u, root->renderSurface()->layerList().size());

    // Damage should be the entire child layer in targetSurface space.
    FloatRect expectedRect = FloatRect(100, 100, 30, 30);
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(expectedRect, rootDamageRect);

    // CASE 2: If a layer moves due to property change, it damages both the new location
    //         and the old (exposed) location. The old location is the entire old layer,
    //         not just the updateRect.

    // Cycle one frame of no change, just to sanity check that the next rect is not because of the old damage state.
    clearDamageForAllSurfaces(root.get());
    emulateDrawingOneFrame(root.get());
    EXPECT_TRUE(root->renderSurface()->damageTracker()->currentDamageRect().isEmpty());

    // Then, test the actual layer movement.
    clearDamageForAllSurfaces(root.get());
    child->setPosition(FloatPoint(200, 230));
    emulateDrawingOneFrame(root.get());

    // Expect damage to be the combination of the previous one and the new one.
    expectedRect.uniteIfNonZero(FloatRect(200, 230, 30, 30));
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(expectedRect, rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForTransformedLayer)
{
    // If a layer is transformed, the damage rect should still enclose the entire
    // transformed layer.

    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child = root->children()[0];

    WebTransformationMatrix rotation;
    rotation.rotate(45);

    clearDamageForAllSurfaces(root.get());
    child->setAnchorPoint(FloatPoint(0.5, 0.5));
    child->setPosition(FloatPoint(85, 85));
    emulateDrawingOneFrame(root.get());

    // Sanity check that the layer actually moved to (85, 85), damaging its old location and new location.
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(85, 85, 45, 45), rootDamageRect);

    // With the anchor on the layer's center, now we can test the rotation more
    // intuitively, since it applies about the layer's anchor.
    clearDamageForAllSurfaces(root.get());
    child->setTransform(rotation);
    emulateDrawingOneFrame(root.get());

    // Since the child layer is square, rotation by 45 degrees about the center should
    // increase the size of the expected rect by sqrt(2), centered around (100, 100). The
    // old exposed region should be fully contained in the new region.
    double expectedWidth = 30 * sqrt(2.0);
    double expectedPosition = 100 - 0.5 * expectedWidth;
    FloatRect expectedRect(expectedPosition, expectedPosition, expectedWidth, expectedWidth);
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(expectedRect, rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForPerspectiveClippedLayer)
{
    // If a layer has a perspective transform that causes w < 0, then not clipping the
    // layer can cause an invalid damage rect. This test checks that the w < 0 case is
    // tracked properly.
    //
    // The transform is constructed so that if w < 0 clipping is not performed, the
    // incorrect rect will be very small, specifically: position (500.972504, 498.544617) and size 0.056610 x 2.910767.
    // Instead, the correctly transformed rect should actually be very huge (i.e. in theory, -infinity on the left),
    // and positioned so that the right-most bound rect will be approximately 501 units in root surface space.
    //

    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child = root->children()[0];

    WebTransformationMatrix transform;
    transform.translate3d(500, 500, 0);
    transform.applyPerspective(1);
    transform.rotate3d(0, 45, 0);
    transform.translate3d(-50, -50, 0);

    // Set up the child
    child->setPosition(FloatPoint(0, 0));
    child->setBounds(IntSize(100, 100));
    child->setContentBounds(IntSize(100, 100));
    child->setTransform(transform);
    emulateDrawingOneFrame(root.get());

    // Sanity check that the child layer's bounds would actually get clipped by w < 0,
    // otherwise this test is not actually testing the intended scenario.
    FloatQuad testQuad(FloatRect(FloatPoint::zero(), FloatSize(100, 100)));
    bool clipped = false;
    CCMathUtil::mapQuad(transform, testQuad, clipped);
    EXPECT_TRUE(clipped);

    // Damage the child without moving it.
    clearDamageForAllSurfaces(root.get());
    child->setOpacity(0.5);
    emulateDrawingOneFrame(root.get());

    // The expected damage should cover the entire root surface (500x500), but we don't
    // care whether the damage rect was clamped or is larger than the surface for this test.
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    FloatRect damageWeCareAbout = FloatRect(FloatPoint::zero(), FloatSize(500, 500));
    EXPECT_TRUE(rootDamageRect.contains(damageWeCareAbout));
}

TEST_F(CCDamageTrackerTest, verifyDamageForBlurredSurface)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child = root->children()[0];

    WebFilterOperations filters;
    filters.append(WebFilterOperation::createBlurFilter(5));
    int outsetTop, outsetRight, outsetBottom, outsetLeft;
    filters.getOutsets(outsetTop, outsetRight, outsetBottom, outsetLeft);

    // Setting the filter will damage the whole surface.
    clearDamageForAllSurfaces(root.get());
    root->setFilters(filters);
    emulateDrawingOneFrame(root.get());

    // Setting the update rect should cause the corresponding damage to the surface, blurred based on the size of the blur filter.
    clearDamageForAllSurfaces(root.get());
    child->setUpdateRect(FloatRect(10, 11, 12, 13));
    emulateDrawingOneFrame(root.get());

    // Damage position on the surface should be: position of updateRect (10, 11) relative to the child (100, 100), but expanded by the blur outsets.
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    FloatRect expectedDamageRect = FloatRect(110, 111, 12, 13);
    expectedDamageRect.move(-outsetLeft, -outsetTop);
    expectedDamageRect.expand(outsetLeft + outsetRight, outsetTop + outsetBottom);
    EXPECT_FLOAT_RECT_EQ(expectedDamageRect, rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForBackgroundBlurredChild)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    CCLayerImpl* child2 = root->children()[1];

    // Allow us to set damage on child1 too.
    child1->setDrawsContent(true);

    WebFilterOperations filters;
    filters.append(WebFilterOperation::createBlurFilter(2));
    int outsetTop, outsetRight, outsetBottom, outsetLeft;
    filters.getOutsets(outsetTop, outsetRight, outsetBottom, outsetLeft);

    // Setting the filter will damage the whole surface.
    clearDamageForAllSurfaces(root.get());
    child1->setBackgroundFilters(filters);
    emulateDrawingOneFrame(root.get());

    // CASE 1: Setting the update rect should cause the corresponding damage to
    // the surface, blurred based on the size of the child's background blur
    // filter.
    clearDamageForAllSurfaces(root.get());
    root->setUpdateRect(FloatRect(297, 297, 2, 2));
    emulateDrawingOneFrame(root.get());

    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    // Damage position on the surface should be a composition of the damage on the root and on child2.
    // Damage on the root should be: position of updateRect (297, 297), but expanded by the blur outsets.
    FloatRect expectedDamageRect = FloatRect(297, 297, 2, 2);
    expectedDamageRect.move(-outsetLeft, -outsetTop);
    expectedDamageRect.expand(outsetLeft + outsetRight, outsetTop + outsetBottom);
    EXPECT_FLOAT_RECT_EQ(expectedDamageRect, rootDamageRect);

    // CASE 2: Setting the update rect should cause the corresponding damage to
    // the surface, blurred based on the size of the child's background blur
    // filter. Since the damage extends to the right/bottom outside of the
    // blurred layer, only the left/top should end up expanded.
    clearDamageForAllSurfaces(root.get());
    root->setUpdateRect(FloatRect(297, 297, 30, 30));
    emulateDrawingOneFrame(root.get());

    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    // Damage position on the surface should be a composition of the damage on the root and on child2.
    // Damage on the root should be: position of updateRect (297, 297), but expanded on the left/top
    // by the blur outsets.
    expectedDamageRect = FloatRect(297, 297, 30, 30);
    expectedDamageRect.move(-outsetLeft, -outsetTop);
    expectedDamageRect.expand(outsetLeft, outsetTop);
    EXPECT_FLOAT_RECT_EQ(expectedDamageRect, rootDamageRect);

    // CASE 3: Setting this update rect outside the blurred contentBounds of the blurred
    // child1 will not cause it to be expanded.
    clearDamageForAllSurfaces(root.get());
    root->setUpdateRect(FloatRect(30, 30, 2, 2));
    emulateDrawingOneFrame(root.get());

    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    // Damage on the root should be: position of updateRect (30, 30), not
    // expanded.
    expectedDamageRect = FloatRect(30, 30, 2, 2);
    EXPECT_FLOAT_RECT_EQ(expectedDamageRect, rootDamageRect);

    // CASE 4: Setting this update rect inside the blurred contentBounds but outside the
    // original contentBounds of the blurred child1 will cause it to be expanded.
    clearDamageForAllSurfaces(root.get());
    root->setUpdateRect(FloatRect(99, 99, 1, 1));
    emulateDrawingOneFrame(root.get());

    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    // Damage on the root should be: position of updateRect (99, 99), expanded
    // by the blurring on child1, but since it is 1 pixel outside the layer, the
    // expanding should be reduced by 1.
    expectedDamageRect = FloatRect(99, 99, 1, 1);
    expectedDamageRect.move(-outsetLeft + 1, -outsetTop + 1);
    expectedDamageRect.expand(outsetLeft + outsetRight - 1, outsetTop + outsetBottom - 1);
    EXPECT_FLOAT_RECT_EQ(expectedDamageRect, rootDamageRect);

    // CASE 5: Setting the update rect on child2, which is above child1, will
    // not get blurred by child1, so it does not need to get expanded.
    clearDamageForAllSurfaces(root.get());
    child2->setUpdateRect(FloatRect(0, 0, 1, 1));
    emulateDrawingOneFrame(root.get());

    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    // Damage on child2 should be: position of updateRect offset by the child's position (11, 11), and not expanded by anything.
    expectedDamageRect = FloatRect(11, 11, 1, 1);
    EXPECT_FLOAT_RECT_EQ(expectedDamageRect, rootDamageRect);

    // CASE 6: Setting the update rect on child1 will also blur the damage, so
    // that any pixels needed for the blur are redrawn in the current frame.
    clearDamageForAllSurfaces(root.get());
    child1->setUpdateRect(FloatRect(0, 0, 1, 1));
    emulateDrawingOneFrame(root.get());

    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    // Damage on child1 should be: position of updateRect offset by the child's position (100, 100), and expanded by the damage.
    expectedDamageRect = FloatRect(100, 100, 1, 1);
    expectedDamageRect.move(-outsetLeft, -outsetTop);
    expectedDamageRect.expand(outsetLeft + outsetRight, outsetTop + outsetBottom);
    EXPECT_FLOAT_RECT_EQ(expectedDamageRect, rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForAddingAndRemovingLayer)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child1 = root->children()[0];

    // CASE 1: Adding a new layer should cause the appropriate damage.
    //
    clearDamageForAllSurfaces(root.get());
    {
        OwnPtr<CCLayerImpl> child2 = CCLayerImpl::create(3);
        child2->setPosition(FloatPoint(400, 380));
        child2->setAnchorPoint(FloatPoint::zero());
        child2->setBounds(IntSize(6, 8));
        child2->setContentBounds(IntSize(6, 8));
        child2->setDrawsContent(true);
        root->addChild(child2.release());
    }
    emulateDrawingOneFrame(root.get());

    // Sanity check - all 3 layers should be on the same render surface; render surfaces are tested elsewhere.
    ASSERT_EQ(3u, root->renderSurface()->layerList().size());

    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(400, 380, 6, 8), rootDamageRect);

    // CASE 2: If the layer is removed, its entire old layer becomes exposed, not just the
    //         last update rect.

    // Advance one frame without damage so that we know the damage rect is not leftover from the previous case.
    clearDamageForAllSurfaces(root.get());
    emulateDrawingOneFrame(root.get());
    EXPECT_TRUE(root->renderSurface()->damageTracker()->currentDamageRect().isEmpty());

    // Then, test removing child1.
    child1->removeFromParent();
    emulateDrawingOneFrame(root.get());
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(100, 100, 30, 30), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForNewUnchangedLayer)
{
    // If child2 is added to the layer tree, but it doesn't have any explicit damage of
    // its own, it should still indeed damage the target surface.

    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();

    clearDamageForAllSurfaces(root.get());
    {
        OwnPtr<CCLayerImpl> child2 = CCLayerImpl::create(3);
        child2->setPosition(FloatPoint(400, 380));
        child2->setAnchorPoint(FloatPoint::zero());
        child2->setBounds(IntSize(6, 8));
        child2->setContentBounds(IntSize(6, 8));
        child2->setDrawsContent(true);
        child2->resetAllChangeTrackingForSubtree();
        // Sanity check the initial conditions of the test, if these asserts trigger, it
        // means the test no longer actually covers the intended scenario.
        ASSERT_FALSE(child2->layerPropertyChanged());
        ASSERT_TRUE(child2->updateRect().isEmpty());
        root->addChild(child2.release());
    }
    emulateDrawingOneFrame(root.get());

    // Sanity check - all 3 layers should be on the same render surface; render surfaces are tested elsewhere.
    ASSERT_EQ(3u, root->renderSurface()->layerList().size());

    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(400, 380, 6, 8), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForMultipleLayers)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child1 = root->children()[0];

    // In this test we don't want the above tree manipulation to be considered part of the same frame.
    clearDamageForAllSurfaces(root.get());
    {
        OwnPtr<CCLayerImpl> child2 = CCLayerImpl::create(3);
        child2->setPosition(FloatPoint(400, 380));
        child2->setAnchorPoint(FloatPoint::zero());
        child2->setBounds(IntSize(6, 8));
        child2->setContentBounds(IntSize(6, 8));
        child2->setDrawsContent(true);
        root->addChild(child2.release());
    }
    CCLayerImpl* child2 = root->children()[1];
    emulateDrawingOneFrame(root.get());

    // Damaging two layers simultaneously should cause combined damage.
    // - child1 update rect in surface space: FloatRect(100, 100, 1, 2);
    // - child2 update rect in surface space: FloatRect(400, 380, 3, 4);
    clearDamageForAllSurfaces(root.get());
    child1->setUpdateRect(FloatRect(0, 0, 1, 2));
    child2->setUpdateRect(FloatRect(0, 0, 3, 4));
    emulateDrawingOneFrame(root.get());
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(100, 100, 303, 284), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForNestedSurfaces)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    CCLayerImpl* child2 = root->children()[1];
    CCLayerImpl* grandChild1 = root->children()[0]->children()[0];
    FloatRect childDamageRect;
    FloatRect rootDamageRect;

    // CASE 1: Damage to a descendant surface should propagate properly to ancestor surface.
    //
    clearDamageForAllSurfaces(root.get());
    grandChild1->setOpacity(0.5);
    emulateDrawingOneFrame(root.get());
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(200, 200, 6, 8), childDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(300, 300, 6, 8), rootDamageRect);

    // CASE 2: Same as previous case, but with additional damage elsewhere that should be properly unioned.
    // - child1 surface damage in root surface space: FloatRect(300, 300, 6, 8);
    // - child2 damage in root surface space: FloatRect(11, 11, 18, 18);
    clearDamageForAllSurfaces(root.get());
    grandChild1->setOpacity(0.7f);
    child2->setOpacity(0.7f);
    emulateDrawingOneFrame(root.get());
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(200, 200, 6, 8), childDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(11, 11, 295, 297), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForSurfaceChangeFromDescendantLayer)
{
    // If descendant layer changes and affects the content bounds of the render surface,
    // then the entire descendant surface should be damaged, and it should damage its
    // ancestor surface with the old and new surface regions.

    // This is a tricky case, since only the first grandChild changes, but the entire
    // surface should be marked dirty.

    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    CCLayerImpl* grandChild1 = root->children()[0]->children()[0];
    FloatRect childDamageRect;
    FloatRect rootDamageRect;

    clearDamageForAllSurfaces(root.get());
    grandChild1->setPosition(FloatPoint(195, 205));
    emulateDrawingOneFrame(root.get());
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();

    // The new surface bounds should be damaged entirely, even though only one of the layers changed.
    EXPECT_FLOAT_RECT_EQ(FloatRect(190, 190, 11, 23), childDamageRect);

    // Damage to the root surface should be the union of child1's *entire* render surface
    // (in target space), and its old exposed area (also in target space).
    EXPECT_FLOAT_RECT_EQ(FloatRect(290, 290, 16, 23), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForSurfaceChangeFromAncestorLayer)
{
    // An ancestor/owning layer changes that affects the position/transform of the render
    // surface. Note that in this case, the layerPropertyChanged flag already propagates
    // to the subtree (tested in CCLayerImpltest), which damages the entire child1
    // surface, but the damage tracker still needs the correct logic to compute the
    // exposed region on the root surface.

    // FIXME: the expectations of this test case should change when we add support for a
    //        unique scissorRect per renderSurface. In that case, the child1 surface
    //        should be completely unchanged, since we are only transforming it, while the
    //        root surface would be damaged appropriately.

    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    FloatRect childDamageRect;
    FloatRect rootDamageRect;

    clearDamageForAllSurfaces(root.get());
    child1->setPosition(FloatPoint(50, 50));
    emulateDrawingOneFrame(root.get());
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();

    // The new surface bounds should be damaged entirely.
    EXPECT_FLOAT_RECT_EQ(FloatRect(190, 190, 16, 18), childDamageRect);

    // The entire child1 surface and the old exposed child1 surface should damage the root surface.
    //  - old child1 surface in target space: FloatRect(290, 290, 16, 18)
    //  - new child1 surface in target space: FloatRect(240, 240, 16, 18)
    EXPECT_FLOAT_RECT_EQ(FloatRect(240, 240, 66, 68), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForAddingAndRemovingRenderSurfaces)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    FloatRect childDamageRect;
    FloatRect rootDamageRect;

    // CASE 1: If a descendant surface disappears, its entire old area becomes exposed.
    //
    clearDamageForAllSurfaces(root.get());
    child1->setOpacity(1);
    emulateDrawingOneFrame(root.get());

    // Sanity check that there is only one surface now.
    ASSERT_FALSE(child1->renderSurface());
    ASSERT_EQ(4u, root->renderSurface()->layerList().size());

    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(290, 290, 16, 18), rootDamageRect);

    // CASE 2: If a descendant surface appears, its entire old area becomes exposed.

    // Cycle one frame of no change, just to sanity check that the next rect is not because of the old damage state.
    clearDamageForAllSurfaces(root.get());
    emulateDrawingOneFrame(root.get());
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_TRUE(rootDamageRect.isEmpty());

    // Then change the tree so that the render surface is added back.
    clearDamageForAllSurfaces(root.get());
    child1->setOpacity(0.5);
    emulateDrawingOneFrame(root.get());

    // Sanity check that there is a new surface now.
    ASSERT_TRUE(child1->renderSurface());
    EXPECT_EQ(3u, root->renderSurface()->layerList().size());
    EXPECT_EQ(2u, child1->renderSurface()->layerList().size());

    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(190, 190, 16, 18), childDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(290, 290, 16, 18), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyNoDamageWhenNothingChanged)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    FloatRect childDamageRect;
    FloatRect rootDamageRect;

    // CASE 1: If nothing changes, the damage rect should be empty.
    //
    clearDamageForAllSurfaces(root.get());
    emulateDrawingOneFrame(root.get());
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_TRUE(childDamageRect.isEmpty());
    EXPECT_TRUE(rootDamageRect.isEmpty());

    // CASE 2: If nothing changes twice in a row, the damage rect should still be empty.
    //
    clearDamageForAllSurfaces(root.get());
    emulateDrawingOneFrame(root.get());
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_TRUE(childDamageRect.isEmpty());
    EXPECT_TRUE(rootDamageRect.isEmpty());
}

TEST_F(CCDamageTrackerTest, verifyNoDamageForUpdateRectThatDoesNotDrawContent)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    FloatRect childDamageRect;
    FloatRect rootDamageRect;

    // In our specific tree, the update rect of child1 should not cause any damage to any
    // surface because it does not actually draw content.
    clearDamageForAllSurfaces(root.get());
    child1->setUpdateRect(FloatRect(0, 0, 1, 2));
    emulateDrawingOneFrame(root.get());
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_TRUE(childDamageRect.isEmpty());
    EXPECT_TRUE(rootDamageRect.isEmpty());
}

TEST_F(CCDamageTrackerTest, verifyDamageForReplica)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    CCLayerImpl* grandChild1 = child1->children()[0];
    CCLayerImpl* grandChild2 = child1->children()[1];

    // Damage on a surface that has a reflection should cause the target surface to
    // receive the surface's damage and the surface's reflected damage.

    // For this test case, we modify grandChild2, and add grandChild3 to extend the bounds
    // of child1's surface. This way, we can test reflection changes without changing
    // contentBounds of the surface.
    grandChild2->setPosition(FloatPoint(180, 180));
    {
        OwnPtr<CCLayerImpl> grandChild3 = CCLayerImpl::create(6);
        grandChild3->setPosition(FloatPoint(240, 240));
        grandChild3->setAnchorPoint(FloatPoint::zero());
        grandChild3->setBounds(IntSize(10, 10));
        grandChild3->setContentBounds(IntSize(10, 10));
        grandChild3->setDrawsContent(true);
        child1->addChild(grandChild3.release());
    }
    child1->setOpacity(0.5);
    emulateDrawingOneFrame(root.get());

    // CASE 1: adding a reflection about the left edge of grandChild1.
    //
    clearDamageForAllSurfaces(root.get());
    {
        OwnPtr<CCLayerImpl> grandChild1Replica = CCLayerImpl::create(7);
        grandChild1Replica->setPosition(FloatPoint::zero());
        grandChild1Replica->setAnchorPoint(FloatPoint::zero());
        WebTransformationMatrix reflection;
        reflection.scale3d(-1, 1, 1);
        grandChild1Replica->setTransform(reflection);
        grandChild1->setReplicaLayer(grandChild1Replica.release());
    }
    emulateDrawingOneFrame(root.get());

    FloatRect grandChildDamageRect = grandChild1->renderSurface()->damageTracker()->currentDamageRect();
    FloatRect childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();

    // The grandChild surface damage should not include its own replica. The child
    // surface damage should include the normal and replica surfaces.
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 6, 8), grandChildDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(194, 200, 12, 8), childDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(294, 300, 12, 8), rootDamageRect);

    // CASE 2: moving the descendant surface should cause both the original and reflected
    //         areas to be damaged on the target.
    clearDamageForAllSurfaces(root.get());
    IntRect oldContentRect = child1->renderSurface()->contentRect();
    grandChild1->setPosition(FloatPoint(195, 205));
    emulateDrawingOneFrame(root.get());
    ASSERT_EQ(oldContentRect.width(), child1->renderSurface()->contentRect().width());
    ASSERT_EQ(oldContentRect.height(), child1->renderSurface()->contentRect().height());

    grandChildDamageRect = grandChild1->renderSurface()->damageTracker()->currentDamageRect();
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();

    // The child surface damage should include normal and replica surfaces for both old and new locations.
    //  - old location in target space: FloatRect(194, 200, 12, 8)
    //  - new location in target space: FloatRect(189, 205, 12, 8)
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 6, 8), grandChildDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(189, 200, 17, 13), childDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(289, 300, 17, 13), rootDamageRect);

    // CASE 3: removing the reflection should cause the entire region including reflection
    //         to damage the target surface.
    clearDamageForAllSurfaces(root.get());
    grandChild1->setReplicaLayer(nullptr);
    emulateDrawingOneFrame(root.get());
    ASSERT_EQ(oldContentRect.width(), child1->renderSurface()->contentRect().width());
    ASSERT_EQ(oldContentRect.height(), child1->renderSurface()->contentRect().height());

    EXPECT_FALSE(grandChild1->renderSurface());
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();

    EXPECT_FLOAT_RECT_EQ(FloatRect(189, 205, 12, 8), childDamageRect);
    EXPECT_FLOAT_RECT_EQ(FloatRect(289, 305, 12, 8), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForMask)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child = root->children()[0];

    // In the current implementation of the damage tracker, changes to mask layers should
    // damage the entire corresponding surface.

    clearDamageForAllSurfaces(root.get());

    // Set up the mask layer.
    {
        OwnPtr<CCLayerImpl> maskLayer = CCLayerImpl::create(3);
        maskLayer->setPosition(child->position());
        maskLayer->setAnchorPoint(FloatPoint::zero());
        maskLayer->setBounds(child->bounds());
        maskLayer->setContentBounds(child->bounds());
        child->setMaskLayer(maskLayer.release());
    }
    CCLayerImpl* maskLayer = child->maskLayer();

    // Add opacity and a grandChild so that the render surface persists even after we remove the mask.
    child->setOpacity(0.5);
    {
        OwnPtr<CCLayerImpl> grandChild = CCLayerImpl::create(4);
        grandChild->setPosition(FloatPoint(2, 2));
        grandChild->setAnchorPoint(FloatPoint::zero());
        grandChild->setBounds(IntSize(2, 2));
        grandChild->setContentBounds(IntSize(2, 2));
        grandChild->setDrawsContent(true);
        child->addChild(grandChild.release());
    }
    emulateDrawingOneFrame(root.get());

    // Sanity check that a new surface was created for the child.
    ASSERT_TRUE(child->renderSurface());

    // CASE 1: the updateRect on a mask layer should damage the entire target surface.
    //
    clearDamageForAllSurfaces(root.get());
    maskLayer->setUpdateRect(FloatRect(1, 2, 3, 4));
    emulateDrawingOneFrame(root.get());
    FloatRect childDamageRect = child->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 30, 30), childDamageRect);

    // CASE 2: a property change on the mask layer should damage the entire target surface.
    //

    // Advance one frame without damage so that we know the damage rect is not leftover from the previous case.
    clearDamageForAllSurfaces(root.get());
    emulateDrawingOneFrame(root.get());
    childDamageRect = child->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_TRUE(childDamageRect.isEmpty());

    // Then test the property change.
    clearDamageForAllSurfaces(root.get());
    maskLayer->setStackingOrderChanged(true);

    emulateDrawingOneFrame(root.get());
    childDamageRect = child->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 30, 30), childDamageRect);

    // CASE 3: removing the mask also damages the entire target surface.
    //

    // Advance one frame without damage so that we know the damage rect is not leftover from the previous case.
    clearDamageForAllSurfaces(root.get());
    emulateDrawingOneFrame(root.get());
    childDamageRect = child->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_TRUE(childDamageRect.isEmpty());

    // Then test mask removal.
    clearDamageForAllSurfaces(root.get());
    child->setMaskLayer(nullptr);
    ASSERT_TRUE(child->layerPropertyChanged());
    emulateDrawingOneFrame(root.get());

    // Sanity check that a render surface still exists.
    ASSERT_TRUE(child->renderSurface());

    childDamageRect = child->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 30, 30), childDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForReplicaMask)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    CCLayerImpl* grandChild1 = child1->children()[0];

    // Changes to a replica's mask should not damage the original surface, because it is
    // not masked. But it does damage the ancestor target surface.

    clearDamageForAllSurfaces(root.get());

    // Create a reflection about the left edge of grandChild1.
    {
        OwnPtr<CCLayerImpl> grandChild1Replica = CCLayerImpl::create(6);
        grandChild1Replica->setPosition(FloatPoint::zero());
        grandChild1Replica->setAnchorPoint(FloatPoint::zero());
        WebTransformationMatrix reflection;
        reflection.scale3d(-1, 1, 1);
        grandChild1Replica->setTransform(reflection);
        grandChild1->setReplicaLayer(grandChild1Replica.release());
    }
    CCLayerImpl* grandChild1Replica = grandChild1->replicaLayer();

    // Set up the mask layer on the replica layer
    {
        OwnPtr<CCLayerImpl> replicaMaskLayer = CCLayerImpl::create(7);
        replicaMaskLayer->setPosition(FloatPoint::zero());
        replicaMaskLayer->setAnchorPoint(FloatPoint::zero());
        replicaMaskLayer->setBounds(grandChild1->bounds());
        replicaMaskLayer->setContentBounds(grandChild1->bounds());
        grandChild1Replica->setMaskLayer(replicaMaskLayer.release());
    }
    CCLayerImpl* replicaMaskLayer = grandChild1Replica->maskLayer();

    emulateDrawingOneFrame(root.get());

    // Sanity check that the appropriate render surfaces were created
    ASSERT_TRUE(grandChild1->renderSurface());

    // CASE 1: a property change on the mask should damage only the reflected region on the target surface.
    clearDamageForAllSurfaces(root.get());
    replicaMaskLayer->setStackingOrderChanged(true);
    emulateDrawingOneFrame(root.get());

    FloatRect grandChildDamageRect = grandChild1->renderSurface()->damageTracker()->currentDamageRect();
    FloatRect childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();

    EXPECT_TRUE(grandChildDamageRect.isEmpty());
    EXPECT_FLOAT_RECT_EQ(FloatRect(194, 200, 6, 8), childDamageRect);

    // CASE 2: removing the replica mask damages only the reflected region on the target surface.
    //
    clearDamageForAllSurfaces(root.get());
    grandChild1Replica->setMaskLayer(nullptr);
    emulateDrawingOneFrame(root.get());

    grandChildDamageRect = grandChild1->renderSurface()->damageTracker()->currentDamageRect();
    childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();

    EXPECT_TRUE(grandChildDamageRect.isEmpty());
    EXPECT_FLOAT_RECT_EQ(FloatRect(194, 200, 6, 8), childDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForReplicaMaskWithAnchor)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithTwoSurfaces();
    CCLayerImpl* child1 = root->children()[0];
    CCLayerImpl* grandChild1 = child1->children()[0];

    // Verify that the correct replicaOriginTransform is used for the replicaMask;
    clearDamageForAllSurfaces(root.get());

    grandChild1->setAnchorPoint(FloatPoint(1, 0)); // This is not exactly the anchor being tested, but by convention its expected to be the same as the replica's anchor point.

    {
        OwnPtr<CCLayerImpl> grandChild1Replica = CCLayerImpl::create(6);
        grandChild1Replica->setPosition(FloatPoint::zero());
        grandChild1Replica->setAnchorPoint(FloatPoint(1, 0)); // This is the anchor being tested.
        WebTransformationMatrix reflection;
        reflection.scale3d(-1, 1, 1);
        grandChild1Replica->setTransform(reflection);
        grandChild1->setReplicaLayer(grandChild1Replica.release());
    }
    CCLayerImpl* grandChild1Replica = grandChild1->replicaLayer();

    // Set up the mask layer on the replica layer
    {
        OwnPtr<CCLayerImpl> replicaMaskLayer = CCLayerImpl::create(7);
        replicaMaskLayer->setPosition(FloatPoint::zero());
        replicaMaskLayer->setAnchorPoint(FloatPoint::zero()); // note, this is not the anchor being tested.
        replicaMaskLayer->setBounds(grandChild1->bounds());
        replicaMaskLayer->setContentBounds(grandChild1->bounds());
        grandChild1Replica->setMaskLayer(replicaMaskLayer.release());
    }
    CCLayerImpl* replicaMaskLayer = grandChild1Replica->maskLayer();

    emulateDrawingOneFrame(root.get());

    // Sanity check that the appropriate render surfaces were created
    ASSERT_TRUE(grandChild1->renderSurface());

    // A property change on the replicaMask should damage the reflected region on the target surface.
    clearDamageForAllSurfaces(root.get());
    replicaMaskLayer->setStackingOrderChanged(true);

    emulateDrawingOneFrame(root.get());

    FloatRect childDamageRect = child1->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(206, 200, 6, 8), childDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageWhenForcedFullDamage)
{
    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child = root->children()[0];

    // Case 1: This test ensures that when the tracker is forced to have full damage, that
    //         it takes priority over any other partial damage.
    //
    clearDamageForAllSurfaces(root.get());
    child->setUpdateRect(FloatRect(10, 11, 12, 13));
    root->renderSurface()->damageTracker()->forceFullDamageNextUpdate();
    emulateDrawingOneFrame(root.get());
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 500, 500), rootDamageRect);

    // Case 2: An additional sanity check that forcing full damage works even when nothing
    //         on the layer tree changed.
    //
    clearDamageForAllSurfaces(root.get());
    root->renderSurface()->damageTracker()->forceFullDamageNextUpdate();
    emulateDrawingOneFrame(root.get());
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(0, 0, 500, 500), rootDamageRect);
}

TEST_F(CCDamageTrackerTest, verifyDamageForEmptyLayerList)
{
    // Though it should never happen, its a good idea to verify that the damage tracker
    // does not crash when it receives an empty layerList.

    OwnPtr<CCLayerImpl> root = CCLayerImpl::create(1);
    root->createRenderSurface();

    ASSERT_TRUE(root == root->renderTarget());
    CCRenderSurface* targetSurface = root->renderSurface();
    targetSurface->clearLayerLists();
    targetSurface->damageTracker()->updateDamageTrackingState(targetSurface->layerList(), targetSurface->owningLayerId(), false, IntRect(), 0, WebFilterOperations());

    FloatRect damageRect = targetSurface->damageTracker()->currentDamageRect();
    EXPECT_TRUE(damageRect.isEmpty());
}

TEST_F(CCDamageTrackerTest, verifyDamageAccumulatesUntilReset)
{
    // If damage is not cleared, it should accumulate.

    OwnPtr<CCLayerImpl> root = createAndSetUpTestTreeWithOneSurface();
    CCLayerImpl* child = root->children()[0];

    clearDamageForAllSurfaces(root.get());
    child->setUpdateRect(FloatRect(10, 11, 1, 2));
    emulateDrawingOneFrame(root.get());

    // Sanity check damage after the first frame; this isnt the actual test yet.
    FloatRect rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(110, 111, 1, 2), rootDamageRect);

    // New damage, without having cleared the previous damage, should be unioned to the previous one.
    child->setUpdateRect(FloatRect(20, 25, 1, 2));
    emulateDrawingOneFrame(root.get());
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_FLOAT_RECT_EQ(FloatRect(110, 111, 11, 16), rootDamageRect);

    // If we notify the damage tracker that we drew the damaged area, then damage should be emptied.
    root->renderSurface()->damageTracker()->didDrawDamagedArea();
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_TRUE(rootDamageRect.isEmpty());

    // Damage should remain empty even after one frame, since there's yet no new damage
    emulateDrawingOneFrame(root.get());
    rootDamageRect = root->renderSurface()->damageTracker()->currentDamageRect();
    EXPECT_TRUE(rootDamageRect.isEmpty());
}

} // namespace