// Copyright 2012 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 "base/containers/hash_tables.h"
#include "cc/animation/scrollbar_animation_controller.h"
#include "cc/layers/append_quads_data.h"
#include "cc/layers/painted_scrollbar_layer.h"
#include "cc/layers/painted_scrollbar_layer_impl.h"
#include "cc/layers/scrollbar_layer_interface.h"
#include "cc/layers/solid_color_scrollbar_layer.h"
#include "cc/layers/solid_color_scrollbar_layer_impl.h"
#include "cc/quads/solid_color_draw_quad.h"
#include "cc/resources/resource_update_queue.h"
#include "cc/test/fake_impl_proxy.h"
#include "cc/test/fake_layer_tree_host.h"
#include "cc/test/fake_layer_tree_host_client.h"
#include "cc/test/fake_layer_tree_host_impl.h"
#include "cc/test/fake_painted_scrollbar_layer.h"
#include "cc/test/fake_scrollbar.h"
#include "cc/test/geometry_test_utils.h"
#include "cc/test/layer_tree_test.h"
#include "cc/test/mock_occlusion_tracker.h"
#include "cc/test/test_web_graphics_context_3d.h"
#include "cc/trees/layer_tree_host.h"
#include "cc/trees/layer_tree_impl.h"
#include "cc/trees/occlusion_tracker.h"
#include "cc/trees/single_thread_proxy.h"
#include "cc/trees/tree_synchronizer.h"
#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace cc {
namespace {

LayerImpl* LayerImplForScrollAreaAndScrollbar(FakeLayerTreeHost* host,
                                              scoped_ptr<Scrollbar> scrollbar,
                                              bool reverse_order,
                                              bool use_solid_color_scrollbar,
                                              int thumb_thickness,
                                              int track_start) {
  scoped_refptr<Layer> layer_tree_root = Layer::Create();
  scoped_refptr<Layer> child1 = Layer::Create();
  scoped_refptr<Layer> child2;
  if (use_solid_color_scrollbar) {
    const bool kIsLeftSideVerticalScrollbar = false;
    child2 = SolidColorScrollbarLayer::Create(scrollbar->Orientation(),
                                              thumb_thickness,
                                              track_start,
                                              kIsLeftSideVerticalScrollbar,
                                              child1->id());
  } else {
    child2 = PaintedScrollbarLayer::Create(scrollbar.Pass(), child1->id());
  }
  child2->ToScrollbarLayer()->SetClipLayer(layer_tree_root->id());
  layer_tree_root->AddChild(child1);
  layer_tree_root->InsertChild(child2, reverse_order ? 0 : 1);
  host->SetRootLayer(layer_tree_root);
  return host->CommitAndCreateLayerImplTree();
}

class FakeResourceTrackingLayerTreeHost : public FakeLayerTreeHost {
 public:
  FakeResourceTrackingLayerTreeHost(FakeLayerTreeHostClient* client,
                                    const LayerTreeSettings& settings)
      : FakeLayerTreeHost(client, settings),
        next_id_(1),
        total_ui_resource_created_(0),
        total_ui_resource_deleted_(0) {
    InitializeSingleThreaded(client, base::MessageLoopProxy::current(),
                             nullptr);
  }

  UIResourceId CreateUIResource(UIResourceClient* content) override {
    total_ui_resource_created_++;
    UIResourceId nid = next_id_++;
    ui_resource_bitmap_map_.insert(
        std::make_pair(nid, content->GetBitmap(nid, false)));
    return nid;
  }

  // Deletes a UI resource.  May safely be called more than once.
  void DeleteUIResource(UIResourceId id) override {
    UIResourceBitmapMap::iterator iter = ui_resource_bitmap_map_.find(id);
    if (iter != ui_resource_bitmap_map_.end()) {
      ui_resource_bitmap_map_.erase(iter);
      total_ui_resource_deleted_++;
    }
  }

  size_t UIResourceCount() { return ui_resource_bitmap_map_.size(); }
  int TotalUIResourceDeleted() { return total_ui_resource_deleted_; }
  int TotalUIResourceCreated() { return total_ui_resource_created_; }

  gfx::Size ui_resource_size(UIResourceId id) {
    UIResourceBitmapMap::iterator iter = ui_resource_bitmap_map_.find(id);
    if (iter != ui_resource_bitmap_map_.end())
      return iter->second.GetSize();
    return gfx::Size();
  }

  UIResourceBitmap* ui_resource_bitmap(UIResourceId id) {
    UIResourceBitmapMap::iterator iter = ui_resource_bitmap_map_.find(id);
    if (iter != ui_resource_bitmap_map_.end())
      return &iter->second;
    return nullptr;
  }

 private:
  using UIResourceBitmapMap = base::hash_map<UIResourceId, UIResourceBitmap>;
  UIResourceBitmapMap ui_resource_bitmap_map_;

  int next_id_;
  int total_ui_resource_created_;
  int total_ui_resource_deleted_;
};

class ScrollbarLayerTest : public testing::Test {
 public:
  ScrollbarLayerTest() : fake_client_(FakeLayerTreeHostClient::DIRECT_3D) {
    layer_tree_settings_.single_thread_proxy_scheduler = false;
    layer_tree_host_.reset(new FakeResourceTrackingLayerTreeHost(
        &fake_client_, layer_tree_settings_));
    fake_client_.SetLayerTreeHost(layer_tree_host_.get());
    // Force output surface creation for renderer capabilities.
    layer_tree_host_->Composite(base::TimeTicks());
    EXPECT_FALSE(layer_tree_host_->output_surface_lost());
  }

 protected:
  FakeLayerTreeHostClient fake_client_;
  LayerTreeSettings layer_tree_settings_;
  scoped_ptr<FakeResourceTrackingLayerTreeHost> layer_tree_host_;
};

TEST_F(ScrollbarLayerTest, ResolveScrollLayerPointer) {
  scoped_ptr<Scrollbar> scrollbar(new FakeScrollbar);
  LayerImpl* layer_impl_tree_root = LayerImplForScrollAreaAndScrollbar(
      layer_tree_host_.get(), scrollbar.Pass(), false, false, 0, 0);

  LayerImpl* cc_child1 = layer_impl_tree_root->children()[0];
  PaintedScrollbarLayerImpl* cc_child2 =
      static_cast<PaintedScrollbarLayerImpl*>(
          layer_impl_tree_root->children()[1]);

  EXPECT_EQ(cc_child1->scrollbars()->size(), 1UL);
  EXPECT_EQ(*(cc_child1->scrollbars()->begin()), cc_child2);
}

TEST_F(ScrollbarLayerTest, ResolveScrollLayerPointer_ReverseOrder) {
  scoped_ptr<Scrollbar> scrollbar(new FakeScrollbar);
  LayerImpl* layer_impl_tree_root = LayerImplForScrollAreaAndScrollbar(
      layer_tree_host_.get(), scrollbar.Pass(), true, false, 0, 0);

  PaintedScrollbarLayerImpl* cc_child1 =
      static_cast<PaintedScrollbarLayerImpl*>(
          layer_impl_tree_root->children()[0]);
  LayerImpl* cc_child2 = layer_impl_tree_root->children()[1];

  EXPECT_EQ(cc_child2->scrollbars()->size(), 1UL);
  EXPECT_EQ(*(cc_child2->scrollbars()->begin()), cc_child1);
}

TEST_F(ScrollbarLayerTest, ShouldScrollNonOverlayOnMainThread) {
  // Create and attach a non-overlay scrollbar.
  scoped_ptr<Scrollbar> scrollbar(new FakeScrollbar);
  LayerImpl* layer_impl_tree_root = LayerImplForScrollAreaAndScrollbar(
      layer_tree_host_.get(), scrollbar.Pass(), false, false, 0, 0);
  PaintedScrollbarLayerImpl* scrollbar_layer_impl =
      static_cast<PaintedScrollbarLayerImpl*>(
          layer_impl_tree_root->children()[1]);

  // When the scrollbar is not an overlay scrollbar, the scroll should be
  // responded to on the main thread as the compositor does not yet implement
  // scrollbar scrolling.
  EXPECT_EQ(
      InputHandler::SCROLL_ON_MAIN_THREAD,
      scrollbar_layer_impl->TryScroll(gfx::Point(0, 0), InputHandler::GESTURE,
                                      SCROLL_BLOCKS_ON_NONE));

  // Create and attach an overlay scrollbar.
  scrollbar.reset(new FakeScrollbar(false, false, true));

  layer_impl_tree_root = LayerImplForScrollAreaAndScrollbar(
      layer_tree_host_.get(), scrollbar.Pass(), false, false, 0, 0);
  scrollbar_layer_impl = static_cast<PaintedScrollbarLayerImpl*>(
      layer_impl_tree_root->children()[1]);

  // The user shouldn't be able to drag an overlay scrollbar and the scroll
  // may be handled in the compositor.
  EXPECT_EQ(
      InputHandler::SCROLL_IGNORED,
      scrollbar_layer_impl->TryScroll(gfx::Point(0, 0), InputHandler::GESTURE,
                                      SCROLL_BLOCKS_ON_NONE));
}

TEST_F(ScrollbarLayerTest, ScrollOffsetSynchronization) {
  scoped_ptr<Scrollbar> scrollbar(new FakeScrollbar);
  scoped_refptr<Layer> layer_tree_root = Layer::Create();
  scoped_refptr<Layer> scroll_layer = Layer::Create();
  scoped_refptr<Layer> content_layer = Layer::Create();
  scoped_refptr<Layer> scrollbar_layer =
      PaintedScrollbarLayer::Create(scrollbar.Pass(), layer_tree_root->id());

  // Choose bounds to give max_scroll_offset = (30, 50).
  layer_tree_root->SetBounds(gfx::Size(70, 150));
  scroll_layer->SetScrollClipLayerId(layer_tree_root->id());
  scroll_layer->SetScrollOffset(gfx::ScrollOffset(10, 20));
  scroll_layer->SetBounds(gfx::Size(100, 200));
  content_layer->SetBounds(gfx::Size(100, 200));

  layer_tree_host_->SetRootLayer(layer_tree_root);
  layer_tree_root->AddChild(scroll_layer);
  scroll_layer->AddChild(content_layer);
  layer_tree_root->AddChild(scrollbar_layer);
  scrollbar_layer->ToScrollbarLayer()->SetScrollLayer(scroll_layer->id());
  scrollbar_layer->ToScrollbarLayer()->SetClipLayer(layer_tree_root->id());

  layer_tree_root->SavePaintProperties();
  content_layer->SavePaintProperties();

  LayerImpl* layer_impl_tree_root =
      layer_tree_host_->CommitAndCreateLayerImplTree();

  ScrollbarLayerImplBase* cc_scrollbar_layer =
      static_cast<PaintedScrollbarLayerImpl*>(
          layer_impl_tree_root->children()[1]);

  EXPECT_EQ(10.f, cc_scrollbar_layer->current_pos());
  EXPECT_EQ(30, cc_scrollbar_layer->maximum());

  layer_tree_root->SetBounds(gfx::Size(700, 1500));
  layer_tree_root->SavePaintProperties();
  scroll_layer->SetBounds(gfx::Size(1000, 2000));
  scroll_layer->SetScrollOffset(gfx::ScrollOffset(100, 200));
  scroll_layer->SavePaintProperties();
  content_layer->SetBounds(gfx::Size(1000, 2000));
  content_layer->SavePaintProperties();

  ScrollbarAnimationController* scrollbar_controller =
      layer_impl_tree_root->scrollbar_animation_controller();
  layer_impl_tree_root = layer_tree_host_->CommitAndCreateLayerImplTree();
  EXPECT_EQ(scrollbar_controller,
            layer_impl_tree_root->scrollbar_animation_controller());

  EXPECT_EQ(100.f, cc_scrollbar_layer->current_pos());
  EXPECT_EQ(300, cc_scrollbar_layer->maximum());

  LayerImpl* scroll_layer_impl = layer_impl_tree_root->children()[0];
  scroll_layer_impl->ScrollBy(gfx::Vector2d(12, 34));

  EXPECT_EQ(112.f, cc_scrollbar_layer->current_pos());
  EXPECT_EQ(300, cc_scrollbar_layer->maximum());
}

#define UPDATE_AND_EXTRACT_LAYER_POINTERS()                                  \
  do {                                                                       \
    scrollbar_layer->UpdateInternalContentScale();                           \
    scrollbar_layer->UpdateThumbAndTrackGeometry();                          \
    root_clip_layer_impl = layer_tree_host_->CommitAndCreateLayerImplTree(); \
    root_layer_impl = root_clip_layer_impl->children()[0];                   \
    scrollbar_layer_impl = static_cast<PaintedScrollbarLayerImpl*>(          \
        root_layer_impl->children()[1]);                                     \
    scrollbar_layer_impl->ScrollbarParametersDidChange(false);               \
  } while (false)

TEST_F(ScrollbarLayerTest, UpdatePropertiesOfScrollBarWhenThumbRemoved) {
  scoped_refptr<Layer> root_clip_layer = Layer::Create();
  scoped_refptr<Layer> root_layer = Layer::Create();
  scoped_refptr<Layer> content_layer = Layer::Create();
  scoped_refptr<FakePaintedScrollbarLayer> scrollbar_layer =
      FakePaintedScrollbarLayer::Create(false, true, root_layer->id());

  root_layer->SetScrollClipLayerId(root_clip_layer->id());
  // Give the root-clip a size that will result in MaxScrollOffset = (80, 0).
  root_clip_layer->SetBounds(gfx::Size(20, 50));
  root_layer->SetBounds(gfx::Size(100, 50));
  content_layer->SetBounds(gfx::Size(100, 50));

  layer_tree_host_->SetRootLayer(root_clip_layer);
  root_clip_layer->AddChild(root_layer);
  root_layer->AddChild(content_layer);
  root_layer->AddChild(scrollbar_layer);

  root_layer->SetScrollOffset(gfx::ScrollOffset(0, 0));
  scrollbar_layer->SetBounds(gfx::Size(70, 10));
  scrollbar_layer->SetScrollLayer(root_layer->id());
  scrollbar_layer->SetClipLayer(root_clip_layer->id());
  scrollbar_layer->fake_scrollbar()->set_location(gfx::Point(20, 10));
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(30, 10, 50, 10));
  scrollbar_layer->fake_scrollbar()->set_thumb_thickness(10);
  scrollbar_layer->fake_scrollbar()->set_thumb_length(4);
  LayerImpl* root_clip_layer_impl = nullptr;
  LayerImpl* root_layer_impl = nullptr;
  PaintedScrollbarLayerImpl* scrollbar_layer_impl = nullptr;

  UPDATE_AND_EXTRACT_LAYER_POINTERS();
  EXPECT_EQ(gfx::Rect(10, 0, 4, 10).ToString(),
            scrollbar_layer_impl->ComputeThumbQuadRect().ToString());

  scrollbar_layer->fake_scrollbar()->set_has_thumb(false);

  UPDATE_AND_EXTRACT_LAYER_POINTERS();
  EXPECT_EQ(gfx::Rect(10, 0, 0, 0).ToString(),
            scrollbar_layer_impl->ComputeThumbQuadRect().ToString());
}

TEST_F(ScrollbarLayerTest, ThumbRect) {
  scoped_refptr<Layer> root_clip_layer = Layer::Create();
  scoped_refptr<Layer> root_layer = Layer::Create();
  scoped_refptr<Layer> content_layer = Layer::Create();
  scoped_refptr<FakePaintedScrollbarLayer> scrollbar_layer =
      FakePaintedScrollbarLayer::Create(false, true, root_layer->id());

  root_layer->SetScrollClipLayerId(root_clip_layer->id());
  // Give the root-clip a size that will result in MaxScrollOffset = (80, 0).
  root_clip_layer->SetBounds(gfx::Size(20, 50));
  root_layer->SetBounds(gfx::Size(100, 50));
  content_layer->SetBounds(gfx::Size(100, 50));

  layer_tree_host_->SetRootLayer(root_clip_layer);
  root_clip_layer->AddChild(root_layer);
  root_layer->AddChild(content_layer);
  root_layer->AddChild(scrollbar_layer);

  root_layer->SetScrollOffset(gfx::ScrollOffset(0, 0));
  scrollbar_layer->SetBounds(gfx::Size(70, 10));
  scrollbar_layer->SetScrollLayer(root_layer->id());
  scrollbar_layer->SetClipLayer(root_clip_layer->id());
  scrollbar_layer->fake_scrollbar()->set_location(gfx::Point(20, 10));
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(30, 10, 50, 10));
  scrollbar_layer->fake_scrollbar()->set_thumb_thickness(10);
  scrollbar_layer->fake_scrollbar()->set_thumb_length(4);
  LayerImpl* root_clip_layer_impl = nullptr;
  LayerImpl* root_layer_impl = nullptr;
  PaintedScrollbarLayerImpl* scrollbar_layer_impl = nullptr;

  // Thumb is at the edge of the scrollbar (should be inset to
  // the start of the track within the scrollbar layer's
  // position).
  UPDATE_AND_EXTRACT_LAYER_POINTERS();
  EXPECT_EQ(gfx::Rect(10, 0, 4, 10).ToString(),
            scrollbar_layer_impl->ComputeThumbQuadRect().ToString());

  // Under-scroll (thumb position should clamp and be unchanged).
  root_layer->SetScrollOffset(gfx::ScrollOffset(-5, 0));

  UPDATE_AND_EXTRACT_LAYER_POINTERS();
  EXPECT_EQ(gfx::Rect(10, 0, 4, 10).ToString(),
            scrollbar_layer_impl->ComputeThumbQuadRect().ToString());

  // Over-scroll (thumb position should clamp on the far side).
  root_layer->SetScrollOffset(gfx::ScrollOffset(85, 0));

  UPDATE_AND_EXTRACT_LAYER_POINTERS();
  EXPECT_EQ(gfx::Rect(56, 0, 4, 10).ToString(),
            scrollbar_layer_impl->ComputeThumbQuadRect().ToString());

  // Change thumb thickness and length.
  scrollbar_layer->fake_scrollbar()->set_thumb_thickness(4);
  scrollbar_layer->fake_scrollbar()->set_thumb_length(6);

  UPDATE_AND_EXTRACT_LAYER_POINTERS();
  EXPECT_EQ(gfx::Rect(54, 0, 6, 4).ToString(),
            scrollbar_layer_impl->ComputeThumbQuadRect().ToString());

  // Shrink the scrollbar layer to cover only the track.
  scrollbar_layer->SetBounds(gfx::Size(50, 10));
  scrollbar_layer->fake_scrollbar()->set_location(gfx::Point(30, 10));
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(30, 10, 50, 10));

  UPDATE_AND_EXTRACT_LAYER_POINTERS();
  EXPECT_EQ(gfx::Rect(44, 0, 6, 4).ToString(),
            scrollbar_layer_impl->ComputeThumbQuadRect().ToString());

  // Shrink the track in the non-scrolling dimension so that it only covers the
  // middle third of the scrollbar layer (this does not affect the thumb
  // position).
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(30, 12, 50, 6));

  UPDATE_AND_EXTRACT_LAYER_POINTERS();
  EXPECT_EQ(gfx::Rect(44, 0, 6, 4).ToString(),
            scrollbar_layer_impl->ComputeThumbQuadRect().ToString());
}

TEST_F(ScrollbarLayerTest, SolidColorDrawQuads) {
  const int kThumbThickness = 3;
  const int kTrackStart = 1;
  const int kTrackLength = 100;

  scoped_ptr<Scrollbar> scrollbar(new FakeScrollbar(false, true, true));
  LayerImpl* layer_impl_tree_root = LayerImplForScrollAreaAndScrollbar(
      layer_tree_host_.get(), scrollbar.Pass(), false, true, kThumbThickness,
      kTrackStart);
  ScrollbarLayerImplBase* scrollbar_layer_impl =
      static_cast<SolidColorScrollbarLayerImpl*>(
          layer_impl_tree_root->children()[1]);
  scrollbar_layer_impl->SetBounds(gfx::Size(kTrackLength, kThumbThickness));
  scrollbar_layer_impl->SetCurrentPos(10.f);
  scrollbar_layer_impl->SetMaximum(100);
  scrollbar_layer_impl->SetVisibleToTotalLengthRatio(0.4f);

  // Thickness should be overridden to 3.
  {
    scoped_ptr<RenderPass> render_pass = RenderPass::Create();
    AppendQuadsData data;
    scrollbar_layer_impl->AppendQuads(render_pass.get(), &data);

    const QuadList& quads = render_pass->quad_list;
    ASSERT_EQ(1u, quads.size());
    EXPECT_EQ(DrawQuad::SOLID_COLOR, quads.front()->material);
    EXPECT_EQ(gfx::Rect(6, 0, 39, 3), quads.front()->rect);
  }

  // Contents scale should scale the draw quad.
  scrollbar_layer_impl->draw_properties().contents_scale_x = 2.f;
  scrollbar_layer_impl->draw_properties().contents_scale_y = 2.f;
  {
    scoped_ptr<RenderPass> render_pass = RenderPass::Create();
    AppendQuadsData data;
    scrollbar_layer_impl->AppendQuads(render_pass.get(), &data);

    const QuadList& quads = render_pass->quad_list;
    ASSERT_EQ(1u, quads.size());
    EXPECT_EQ(DrawQuad::SOLID_COLOR, quads.front()->material);
    EXPECT_EQ(gfx::Rect(12, 0, 78, 6), quads.front()->rect);
  }
  scrollbar_layer_impl->draw_properties().contents_scale_x = 1.f;
  scrollbar_layer_impl->draw_properties().contents_scale_y = 1.f;

  // For solid color scrollbars, position and size should reflect the
  // current viewport state.
  scrollbar_layer_impl->SetVisibleToTotalLengthRatio(0.2f);
  {
    scoped_ptr<RenderPass> render_pass = RenderPass::Create();
    AppendQuadsData data;
    scrollbar_layer_impl->AppendQuads(render_pass.get(), &data);

    const QuadList& quads = render_pass->quad_list;
    ASSERT_EQ(1u, quads.size());
    EXPECT_EQ(DrawQuad::SOLID_COLOR, quads.front()->material);
    EXPECT_EQ(gfx::Rect(8, 0, 19, 3), quads.front()->rect);
  }

  // We shouldn't attempt div-by-zero when the maximum is zero.
  scrollbar_layer_impl->SetCurrentPos(0.f);
  scrollbar_layer_impl->SetMaximum(0);
  {
    scoped_ptr<RenderPass> render_pass = RenderPass::Create();
    AppendQuadsData data;
    scrollbar_layer_impl->AppendQuads(render_pass.get(), &data);

    const QuadList& quads = render_pass->quad_list;
    ASSERT_EQ(1u, quads.size());
    EXPECT_EQ(DrawQuad::SOLID_COLOR, quads.front()->material);
    EXPECT_EQ(gfx::Rect(1, 0, 19, 3), quads.front()->rect);
  }
}

TEST_F(ScrollbarLayerTest, LayerDrivenSolidColorDrawQuads) {
  const int kThumbThickness = 3;
  const int kTrackStart = 0;
  const int kTrackLength = 10;

  scoped_ptr<Scrollbar> scrollbar(new FakeScrollbar(false, true, true));

  {
    scoped_refptr<Layer> layer_tree_root = Layer::Create();
    scoped_refptr<Layer> scroll_layer = Layer::Create();
    scroll_layer->SetScrollClipLayerId(layer_tree_root->id());
    scoped_refptr<Layer> child1 = Layer::Create();
    scoped_refptr<Layer> child2;
    const bool kIsLeftSideVerticalScrollbar = false;
    child2 = SolidColorScrollbarLayer::Create(scrollbar->Orientation(),
                                              kThumbThickness,
                                              kTrackStart,
                                              kIsLeftSideVerticalScrollbar,
                                              child1->id());
    child2->ToScrollbarLayer()->SetScrollLayer(scroll_layer->id());
    child2->ToScrollbarLayer()->SetClipLayer(layer_tree_root->id());
    scroll_layer->AddChild(child1);
    scroll_layer->InsertChild(child2, 1);
    layer_tree_root->AddChild(scroll_layer);
    layer_tree_host_->SetRootLayer(layer_tree_root);
  }
  LayerImpl* layer_impl_tree_root =
      layer_tree_host_->CommitAndCreateLayerImplTree();
  LayerImpl* scroll_layer_impl = layer_impl_tree_root->children()[0];

  ScrollbarLayerImplBase* scrollbar_layer_impl =
      static_cast<PaintedScrollbarLayerImpl*>(scroll_layer_impl->children()[1]);

  // Choose layer bounds to give max_scroll_offset = (8, 8).
  layer_impl_tree_root->SetBounds(gfx::Size(2, 2));
  scroll_layer_impl->SetBounds(gfx::Size(10, 10));
  scroll_layer_impl->ScrollBy(gfx::Vector2dF(4.f, 0.f));

  scrollbar_layer_impl->SetBounds(gfx::Size(kTrackLength, kThumbThickness));
  scrollbar_layer_impl->SetCurrentPos(4.f);
  scrollbar_layer_impl->SetMaximum(8);

  {
    scoped_ptr<RenderPass> render_pass = RenderPass::Create();

    AppendQuadsData data;
    scrollbar_layer_impl->AppendQuads(render_pass.get(), &data);

    const QuadList& quads = render_pass->quad_list;
    ASSERT_EQ(1u, quads.size());
    EXPECT_EQ(DrawQuad::SOLID_COLOR, quads.front()->material);
    EXPECT_EQ(gfx::Rect(3, 0, 3, 3), quads.front()->rect);
  }
}

class ScrollbarLayerSolidColorThumbTest : public testing::Test {
 public:
  ScrollbarLayerSolidColorThumbTest() {
    LayerTreeSettings layer_tree_settings;
    host_impl_.reset(new FakeLayerTreeHostImpl(
        layer_tree_settings, &proxy_, &shared_bitmap_manager_));

    const int kThumbThickness = 3;
    const int kTrackStart = 0;
    const bool kIsLeftSideVerticalScrollbar = false;
    const bool kIsOverlayScrollbar = false;

    horizontal_scrollbar_layer_ =
        SolidColorScrollbarLayerImpl::Create(host_impl_->active_tree(),
                                             1,
                                             HORIZONTAL,
                                             kThumbThickness,
                                             kTrackStart,
                                             kIsLeftSideVerticalScrollbar,
                                             kIsOverlayScrollbar);
    vertical_scrollbar_layer_ =
        SolidColorScrollbarLayerImpl::Create(host_impl_->active_tree(),
                                             2,
                                             VERTICAL,
                                             kThumbThickness,
                                             kTrackStart,
                                             kIsLeftSideVerticalScrollbar,
                                             kIsOverlayScrollbar);
  }

 protected:
  FakeImplProxy proxy_;
  TestSharedBitmapManager shared_bitmap_manager_;
  scoped_ptr<FakeLayerTreeHostImpl> host_impl_;
  scoped_ptr<SolidColorScrollbarLayerImpl> horizontal_scrollbar_layer_;
  scoped_ptr<SolidColorScrollbarLayerImpl> vertical_scrollbar_layer_;
};

TEST_F(ScrollbarLayerSolidColorThumbTest, SolidColorThumbLength) {
  horizontal_scrollbar_layer_->SetCurrentPos(0);
  horizontal_scrollbar_layer_->SetMaximum(10);

  // Simple case - one third of the scrollable area is visible, so the thumb
  // should be one third as long as the track.
  horizontal_scrollbar_layer_->SetVisibleToTotalLengthRatio(0.33f);
  horizontal_scrollbar_layer_->SetBounds(gfx::Size(100, 3));
  EXPECT_EQ(33, horizontal_scrollbar_layer_->ComputeThumbQuadRect().width());

  // The thumb's length should never be less than its thickness.
  horizontal_scrollbar_layer_->SetVisibleToTotalLengthRatio(0.01f);
  horizontal_scrollbar_layer_->SetBounds(gfx::Size(100, 3));
  EXPECT_EQ(3, horizontal_scrollbar_layer_->ComputeThumbQuadRect().width());
}

TEST_F(ScrollbarLayerSolidColorThumbTest, SolidColorThumbPosition) {
  horizontal_scrollbar_layer_->SetBounds(gfx::Size(100, 3));
  horizontal_scrollbar_layer_->SetVisibleToTotalLengthRatio(0.1f);

  horizontal_scrollbar_layer_->SetCurrentPos(0);
  horizontal_scrollbar_layer_->SetMaximum(100);
  EXPECT_EQ(0, horizontal_scrollbar_layer_->ComputeThumbQuadRect().x());
  EXPECT_EQ(10, horizontal_scrollbar_layer_->ComputeThumbQuadRect().width());

  horizontal_scrollbar_layer_->SetCurrentPos(100);
  // The thumb is 10px long and the track is 100px, so the maximum thumb
  // position is 90px.
  EXPECT_EQ(90, horizontal_scrollbar_layer_->ComputeThumbQuadRect().x());

  horizontal_scrollbar_layer_->SetCurrentPos(80);
  // The scroll position is 80% of the maximum, so the thumb's position should
  // be at 80% of its maximum or 72px.
  EXPECT_EQ(72, horizontal_scrollbar_layer_->ComputeThumbQuadRect().x());
}

TEST_F(ScrollbarLayerSolidColorThumbTest, SolidColorThumbVerticalAdjust) {
  SolidColorScrollbarLayerImpl* layers[2] =
      { horizontal_scrollbar_layer_.get(), vertical_scrollbar_layer_.get() };
  for (size_t i = 0; i < 2; ++i) {
    layers[i]->SetVisibleToTotalLengthRatio(0.2f);
    layers[i]->SetCurrentPos(25);
    layers[i]->SetMaximum(100);
  }
  layers[0]->SetBounds(gfx::Size(100, 3));
  layers[1]->SetBounds(gfx::Size(3, 100));

  EXPECT_EQ(gfx::RectF(20.f, 0.f, 20.f, 3.f),
            horizontal_scrollbar_layer_->ComputeThumbQuadRect());
  EXPECT_EQ(gfx::RectF(0.f, 20.f, 3.f, 20.f),
            vertical_scrollbar_layer_->ComputeThumbQuadRect());

  horizontal_scrollbar_layer_->SetVerticalAdjust(10.f);
  vertical_scrollbar_layer_->SetVerticalAdjust(10.f);

  // The vertical adjustment factor has two effects:
  // 1.) Moves the horizontal scrollbar down
  // 2.) Increases the vertical scrollbar's effective track length which both
  // increases the thumb's length and its position within the track.
  EXPECT_EQ(gfx::Rect(20.f, 10.f, 20.f, 3.f),
            horizontal_scrollbar_layer_->ComputeThumbQuadRect());
  EXPECT_EQ(gfx::Rect(0.f, 22, 3.f, 22.f),
            vertical_scrollbar_layer_->ComputeThumbQuadRect());
}

class ScrollbarLayerTestMaxTextureSize : public LayerTreeTest {
 public:
  ScrollbarLayerTestMaxTextureSize() {}

  void SetScrollbarBounds(const gfx::Size& bounds) { bounds_ = bounds; }

  void BeginTest() override {
    scroll_layer_ = Layer::Create();
    layer_tree_host()->root_layer()->AddChild(scroll_layer_);

    scoped_ptr<Scrollbar> scrollbar(new FakeScrollbar);
    scrollbar_layer_ =
        PaintedScrollbarLayer::Create(scrollbar.Pass(), scroll_layer_->id());
    scrollbar_layer_->SetScrollLayer(scroll_layer_->id());
    scrollbar_layer_->SetLayerTreeHost(layer_tree_host());
    scrollbar_layer_->SetBounds(bounds_);
    scrollbar_layer_->SetIsDrawable(true);
    layer_tree_host()->root_layer()->AddChild(scrollbar_layer_);

    PostSetNeedsCommitToMainThread();
  }

  void DidCommitAndDrawFrame() override {
    const int kMaxTextureSize =
        layer_tree_host()->GetRendererCapabilities().max_texture_size;

    // Check first that we're actually testing something.
    EXPECT_GT(scrollbar_layer_->bounds().width(), kMaxTextureSize);

    EXPECT_EQ(scrollbar_layer_->internal_content_bounds().width(),
              kMaxTextureSize - 1);
    EXPECT_EQ(scrollbar_layer_->internal_content_bounds().height(),
              kMaxTextureSize - 1);

    EndTest();
  }

  void AfterTest() override {}

 private:
  scoped_refptr<PaintedScrollbarLayer> scrollbar_layer_;
  scoped_refptr<Layer> scroll_layer_;
  gfx::Size bounds_;
};

TEST_F(ScrollbarLayerTestMaxTextureSize, DirectRenderer) {
  scoped_ptr<TestWebGraphicsContext3D> context =
      TestWebGraphicsContext3D::Create();
  int max_size = 0;
  context->getIntegerv(GL_MAX_TEXTURE_SIZE, &max_size);
  SetScrollbarBounds(gfx::Size(max_size + 100, max_size + 100));
  RunTest(true, false, true);
}

TEST_F(ScrollbarLayerTestMaxTextureSize, DelegatingRenderer) {
  scoped_ptr<TestWebGraphicsContext3D> context =
      TestWebGraphicsContext3D::Create();
  int max_size = 0;
  context->getIntegerv(GL_MAX_TEXTURE_SIZE, &max_size);
  SetScrollbarBounds(gfx::Size(max_size + 100, max_size + 100));
  RunTest(true, true, true);
}

class ScrollbarLayerTestResourceCreationAndRelease : public ScrollbarLayerTest {
 public:
  void TestResourceUpload(int num_updates,
                          size_t expected_resources,
                          int expected_created,
                          int expected_deleted,
                          bool use_solid_color_scrollbar) {
    scoped_ptr<Scrollbar> scrollbar(new FakeScrollbar(false, true, false));
    scoped_refptr<Layer> layer_tree_root = Layer::Create();
    scoped_refptr<Layer> content_layer = Layer::Create();
    scoped_refptr<Layer> scrollbar_layer;
    if (use_solid_color_scrollbar) {
      const int kThumbThickness = 3;
      const int kTrackStart = 0;
      const bool kIsLeftSideVerticalScrollbar = false;
      scrollbar_layer =
          SolidColorScrollbarLayer::Create(scrollbar->Orientation(),
                                           kThumbThickness,
                                           kTrackStart,
                                           kIsLeftSideVerticalScrollbar,
                                           layer_tree_root->id());
    } else {
      scrollbar_layer = PaintedScrollbarLayer::Create(scrollbar.Pass(),
                                                      layer_tree_root->id());
    }
    layer_tree_root->AddChild(content_layer);
    layer_tree_root->AddChild(scrollbar_layer);

    layer_tree_host_->SetRootLayer(layer_tree_root);

    scrollbar_layer->SetIsDrawable(true);
    scrollbar_layer->SetBounds(gfx::Size(100, 100));
    layer_tree_root->SetScrollOffset(gfx::ScrollOffset(10, 20));
    layer_tree_root->SetBounds(gfx::Size(100, 200));
    content_layer->SetBounds(gfx::Size(100, 200));
    scrollbar_layer->draw_properties().content_bounds = gfx::Size(100, 200);
    scrollbar_layer->draw_properties().visible_content_rect =
        gfx::Rect(0, 0, 100, 200);
    scrollbar_layer->CreateRenderSurface();
    scrollbar_layer->draw_properties().render_target = scrollbar_layer.get();

    testing::Mock::VerifyAndClearExpectations(layer_tree_host_.get());
    EXPECT_EQ(scrollbar_layer->layer_tree_host(), layer_tree_host_.get());

    ResourceUpdateQueue queue;
    gfx::Rect screen_space_clip_rect;
    OcclusionTracker<Layer> occlusion_tracker(screen_space_clip_rect);

    scrollbar_layer->SavePaintProperties();
    for (int update_counter = 0; update_counter < num_updates; update_counter++)
      scrollbar_layer->Update(&queue, &occlusion_tracker);

    // A non-solid-color scrollbar should have requested two textures.
    EXPECT_EQ(expected_resources, layer_tree_host_->UIResourceCount());
    EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
    EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());

    testing::Mock::VerifyAndClearExpectations(layer_tree_host_.get());

    scrollbar_layer->ClearRenderSurface();
  }
};

TEST_F(ScrollbarLayerTestResourceCreationAndRelease, ResourceUpload) {
  bool use_solid_color_scrollbars = false;
  TestResourceUpload(0, 0, 0, 0, use_solid_color_scrollbars);
  int num_updates[3] = {1, 5, 10};
  int created = 0;
  int deleted = 0;
  for (int j = 0; j < 3; j++) {
    created += num_updates[j] * 2;
    deleted = created - 2;
    TestResourceUpload(num_updates[j], 2, created, deleted,
                       use_solid_color_scrollbars);
  }
}

TEST_F(ScrollbarLayerTestResourceCreationAndRelease,
       SolidColorNoResourceUpload) {
  bool use_solid_color_scrollbars = true;
  TestResourceUpload(0, 0, 0, 0, use_solid_color_scrollbars);
  TestResourceUpload(1, 0, 0, 0, use_solid_color_scrollbars);
}

TEST_F(ScrollbarLayerTestResourceCreationAndRelease, TestResourceUpdate) {
  gfx::Point scrollbar_location(0, 185);
  scoped_refptr<Layer> layer_tree_root = Layer::Create();
  scoped_refptr<Layer> content_layer = Layer::Create();
  scoped_refptr<FakePaintedScrollbarLayer> scrollbar_layer =
      FakePaintedScrollbarLayer::Create(false, true, layer_tree_root->id());

  layer_tree_root->AddChild(content_layer);
  layer_tree_root->AddChild(scrollbar_layer);

  layer_tree_host_->SetRootLayer(layer_tree_root);

  scrollbar_layer->SetIsDrawable(true);
  scrollbar_layer->SetBounds(gfx::Size(100, 15));
  scrollbar_layer->SetPosition(scrollbar_location);
  layer_tree_root->SetBounds(gfx::Size(100, 200));
  content_layer->SetBounds(gfx::Size(100, 200));

  scrollbar_layer->draw_properties().content_bounds = gfx::Size(100, 200);
  scrollbar_layer->draw_properties().visible_content_rect =
      gfx::Rect(0, 0, 100, 200);

  scrollbar_layer->CreateRenderSurface();
  scrollbar_layer->draw_properties().render_target = scrollbar_layer.get();

  testing::Mock::VerifyAndClearExpectations(layer_tree_host_.get());
  EXPECT_EQ(scrollbar_layer->layer_tree_host(), layer_tree_host_.get());

  ResourceUpdateQueue queue;
  gfx::Rect screen_space_clip_rect;
  size_t resource_count;
  int expected_created, expected_deleted;
  OcclusionTracker<Layer> occlusion_tracker(screen_space_clip_rect);
  scrollbar_layer->SavePaintProperties();

  resource_count = 2;
  expected_created = 2;
  expected_deleted = 0;
  EXPECT_TRUE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_NE(0, scrollbar_layer->track_resource_id());
  EXPECT_NE(0, scrollbar_layer->thumb_resource_id());
  EXPECT_EQ(resource_count, layer_tree_host_->UIResourceCount());
  EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
  EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());

  resource_count = 0;
  expected_created = 2;
  expected_deleted = 2;
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(0, 0, 0, 0));
  EXPECT_TRUE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_EQ(0, scrollbar_layer->track_resource_id());
  EXPECT_EQ(0, scrollbar_layer->thumb_resource_id());
  EXPECT_EQ(resource_count, layer_tree_host_->UIResourceCount());
  EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
  EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());

  resource_count = 0;
  expected_created = 2;
  expected_deleted = 2;
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(0, 0, 0, 0));
  EXPECT_FALSE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_EQ(0, scrollbar_layer->track_resource_id());
  EXPECT_EQ(0, scrollbar_layer->thumb_resource_id());
  EXPECT_EQ(resource_count, layer_tree_host_->UIResourceCount());
  EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
  EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());

  resource_count = 2;
  expected_created = 4;
  expected_deleted = 2;
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(30, 10, 50, 10));
  EXPECT_TRUE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_NE(0, scrollbar_layer->track_resource_id());
  EXPECT_NE(0, scrollbar_layer->thumb_resource_id());
  EXPECT_EQ(resource_count, layer_tree_host_->UIResourceCount());
  EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
  EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());

  resource_count = 1;
  expected_created = 5;
  expected_deleted = 4;
  scrollbar_layer->fake_scrollbar()->set_has_thumb(false);
  EXPECT_TRUE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_NE(0, scrollbar_layer->track_resource_id());
  EXPECT_EQ(0, scrollbar_layer->thumb_resource_id());
  EXPECT_EQ(resource_count, layer_tree_host_->UIResourceCount());
  EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
  EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());

  resource_count = 0;
  expected_created = 5;
  expected_deleted = 5;
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(0, 0, 0, 0));
  EXPECT_TRUE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_EQ(0, scrollbar_layer->track_resource_id());
  EXPECT_EQ(0, scrollbar_layer->thumb_resource_id());
  EXPECT_EQ(resource_count, layer_tree_host_->UIResourceCount());
  EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
  EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());

  resource_count = 2;
  expected_created = 7;
  expected_deleted = 5;
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(30, 10, 50, 10));
  scrollbar_layer->fake_scrollbar()->set_has_thumb(true);
  EXPECT_TRUE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_NE(0, scrollbar_layer->track_resource_id());
  EXPECT_NE(0, scrollbar_layer->thumb_resource_id());

  resource_count = 1;
  expected_created = 8;
  expected_deleted = 7;
  scrollbar_layer->fake_scrollbar()->set_track_rect(gfx::Rect(30, 10, 50, 10));
  scrollbar_layer->fake_scrollbar()->set_has_thumb(false);
  scrollbar_layer->SetBounds(gfx::Size(90, 15));
  EXPECT_TRUE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_EQ(resource_count, layer_tree_host_->UIResourceCount());
  EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
  EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());
  EXPECT_EQ(
      gfx::Size(90, 15),
      layer_tree_host_->ui_resource_size(scrollbar_layer->track_resource_id()));

  scrollbar_layer->ResetNeedsDisplayForTesting();
  EXPECT_FALSE(scrollbar_layer->Update(&queue, &occlusion_tracker));
  EXPECT_NE(0, scrollbar_layer->track_resource_id());
  EXPECT_EQ(0, scrollbar_layer->thumb_resource_id());
  EXPECT_EQ(resource_count, layer_tree_host_->UIResourceCount());
  EXPECT_EQ(expected_created, layer_tree_host_->TotalUIResourceCreated());
  EXPECT_EQ(expected_deleted, layer_tree_host_->TotalUIResourceDeleted());

  testing::Mock::VerifyAndClearExpectations(layer_tree_host_.get());
  scrollbar_layer->ClearRenderSurface();
}

class ScaledScrollbarLayerTestResourceCreation : public ScrollbarLayerTest {
 public:
  void TestResourceUpload(const float test_scale) {
    gfx::Point scrollbar_location(0, 185);
    scoped_refptr<Layer> layer_tree_root = Layer::Create();
    scoped_refptr<Layer> content_layer = Layer::Create();
    scoped_refptr<FakePaintedScrollbarLayer> scrollbar_layer =
        FakePaintedScrollbarLayer::Create(false, true, layer_tree_root->id());

    layer_tree_root->AddChild(content_layer);
    layer_tree_root->AddChild(scrollbar_layer);

    layer_tree_host_->SetRootLayer(layer_tree_root);

    scrollbar_layer->SetIsDrawable(true);
    scrollbar_layer->SetBounds(gfx::Size(100, 15));
    scrollbar_layer->SetPosition(scrollbar_location);
    layer_tree_root->SetBounds(gfx::Size(100, 200));
    content_layer->SetBounds(gfx::Size(100, 200));
    gfx::SizeF scaled_size =
        gfx::ScaleSize(scrollbar_layer->bounds(), test_scale, test_scale);
    gfx::PointF scaled_location =
        gfx::ScalePoint(scrollbar_layer->position(), test_scale, test_scale);
    scrollbar_layer->draw_properties().content_bounds =
        gfx::Size(scaled_size.width(), scaled_size.height());
    scrollbar_layer->draw_properties().contents_scale_x = test_scale;
    scrollbar_layer->draw_properties().contents_scale_y = test_scale;
    scrollbar_layer->draw_properties().visible_content_rect =
        gfx::Rect(scaled_location.x(),
                  scaled_location.y(),
                  scaled_size.width(),
                  scaled_size.height());
    scrollbar_layer->CreateRenderSurface();
    scrollbar_layer->draw_properties().render_target = scrollbar_layer.get();

    testing::Mock::VerifyAndClearExpectations(layer_tree_host_.get());
    EXPECT_EQ(scrollbar_layer->layer_tree_host(), layer_tree_host_.get());

    ResourceUpdateQueue queue;
    gfx::Rect screen_space_clip_rect;
    OcclusionTracker<Layer> occlusion_tracker(screen_space_clip_rect);
    scrollbar_layer->SavePaintProperties();
    scrollbar_layer->Update(&queue, &occlusion_tracker);

    // Verify that we have not generated any content uploads that are larger
    // than their destination textures.

    gfx::Size track_size = layer_tree_host_->ui_resource_size(
        scrollbar_layer->track_resource_id());
    gfx::Size thumb_size = layer_tree_host_->ui_resource_size(
        scrollbar_layer->thumb_resource_id());

    EXPECT_LE(track_size.width(),
              scrollbar_layer->internal_content_bounds().width());
    EXPECT_LE(track_size.height(),
              scrollbar_layer->internal_content_bounds().height());
    EXPECT_LE(thumb_size.width(),
              scrollbar_layer->internal_content_bounds().width());
    EXPECT_LE(thumb_size.height(),
              scrollbar_layer->internal_content_bounds().height());

    testing::Mock::VerifyAndClearExpectations(layer_tree_host_.get());

    scrollbar_layer->ClearRenderSurface();
  }
};

TEST_F(ScaledScrollbarLayerTestResourceCreation, ScaledResourceUpload) {
  // Pick a test scale that moves the scrollbar's (non-zero) position to
  // a non-pixel-aligned location.
  TestResourceUpload(.041f);
  TestResourceUpload(1.41f);
  TestResourceUpload(4.1f);
}

class ScaledScrollbarLayerTestScaledRasterization : public ScrollbarLayerTest {
 public:
  void TestScale(const gfx::Rect scrollbar_rect, const float test_scale) {
    bool paint_during_update = true;
    bool has_thumb = false;
    scoped_refptr<Layer> layer_tree_root = Layer::Create();
    scoped_refptr<FakePaintedScrollbarLayer> scrollbar_layer =
        FakePaintedScrollbarLayer::Create(paint_during_update,
                                          has_thumb,
                                          layer_tree_root->id());

    layer_tree_root->AddChild(scrollbar_layer);

    layer_tree_host_->SetRootLayer(layer_tree_root);

    scrollbar_layer->SetBounds(scrollbar_rect.size());
    scrollbar_layer->SetPosition(scrollbar_rect.origin());
    scrollbar_layer->fake_scrollbar()->set_location(scrollbar_rect.origin());
    scrollbar_layer->fake_scrollbar()->set_track_rect(scrollbar_rect);
    gfx::SizeF scaled_size =
        gfx::ScaleSize(scrollbar_layer->bounds(), test_scale, test_scale);
    gfx::PointF scaled_location =
        gfx::ScalePoint(scrollbar_layer->position(), test_scale, test_scale);
    scrollbar_layer->draw_properties().content_bounds =
        gfx::Size(scaled_size.width(), scaled_size.height());
    scrollbar_layer->draw_properties().contents_scale_x = test_scale;
    scrollbar_layer->draw_properties().contents_scale_y = test_scale;
    scrollbar_layer->draw_properties().visible_content_rect =
        gfx::Rect(scaled_location.x(),
                  scaled_location.y(),
                  scaled_size.width(),
                  scaled_size.height());

    ResourceUpdateQueue queue;
    gfx::Rect screen_space_clip_rect;
    OcclusionTracker<Layer> occlusion_tracker(screen_space_clip_rect);
    scrollbar_layer->SavePaintProperties();

    scrollbar_layer->Update(&queue, &occlusion_tracker);

    UIResourceBitmap* bitmap = layer_tree_host_->ui_resource_bitmap(
        scrollbar_layer->track_resource_id());

    DCHECK(bitmap);

    AutoLockUIResourceBitmap locked_bitmap(*bitmap);

    const SkColor* pixels =
        reinterpret_cast<const SkColor*>(locked_bitmap.GetPixels());
    SkColor color = argb_to_skia(
        scrollbar_layer->fake_scrollbar()->paint_fill_color());
    int width = bitmap->GetSize().width();
    int height = bitmap->GetSize().height();

    // Make sure none of the corners of the bitmap were inadvertently clipped.
    EXPECT_EQ(color, pixels[0])
        << "Top left pixel doesn't match scrollbar color.";

    EXPECT_EQ(color, pixels[width - 1])
        << "Top right pixel doesn't match scrollbar color.";

    EXPECT_EQ(color, pixels[width * (height - 1)])
        << "Bottom left pixel doesn't match scrollbar color.";

    EXPECT_EQ(color, pixels[width * height - 1])
        << "Bottom right pixel doesn't match scrollbar color.";
  }

 protected:
  // On Android, Skia uses ABGR
  static SkColor argb_to_skia(SkColor c) {
      return (SkColorGetA(c) << SK_A32_SHIFT) |
             (SkColorGetR(c) << SK_R32_SHIFT) |
             (SkColorGetG(c) << SK_G32_SHIFT) |
             (SkColorGetB(c) << SK_B32_SHIFT);
  }
};

TEST_F(ScaledScrollbarLayerTestScaledRasterization, TestLostPrecisionInClip) {
  // Try rasterization at coordinates and scale that caused problematic
  // rounding and clipping errors.
  // Vertical Scrollbars.
  TestScale(gfx::Rect(1240, 0, 15, 1333), 2.7754839f);
  TestScale(gfx::Rect(1240, 0, 15, 677), 2.46677136f);

  // Horizontal Scrollbars.
  TestScale(gfx::Rect(0, 1240, 1333, 15), 2.7754839f);
  TestScale(gfx::Rect(0, 1240, 677, 15), 2.46677136f);
}

}  // namespace
}  // namespace cc