cc: Move worker threads to RenderThreadImpl.

This allows us to Join the threads when RenderThreadImpl
is shutdown.

BUG=468785
TEST=cc_unittests

Review URL: https://codereview.chromium.org/999173004

Cr-Commit-Position: refs/heads/master@{#321836}

15 files changed, 110 insertions, 143 deletions

diff --git a/cc/trees/damage_tracker_unittest.cc b/cc/trees/damage_tracker_unittest.cc
index 95609d3..2df71dd 100644
--- a/cc/trees/damage_tracker_unittest.cc
+++ b/cc/trees/damage_tracker_unittest.cc
@@ -12,6 +12,7 @@
 #include "cc/test/fake_layer_tree_host_impl.h"
 #include "cc/test/geometry_test_utils.h"
 #include "cc/test/test_shared_bitmap_manager.h"
+#include "cc/test/test_task_graph_runner.h"
 #include "cc/trees/layer_tree_host_common.h"
 #include "cc/trees/single_thread_proxy.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -74,7 +75,8 @@ void EmulateDrawingOneFrame(LayerImpl* root) {
 
 class DamageTrackerTest : public testing::Test {
  public:
-  DamageTrackerTest() : host_impl_(&proxy_, &shared_bitmap_manager_) {}
+  DamageTrackerTest()
+      : host_impl_(&proxy_, &shared_bitmap_manager_, &task_graph_runner_) {}
 
   scoped_ptr<LayerImpl> CreateTestTreeWithOneSurface() {
     scoped_ptr<LayerImpl> root =
@@ -176,6 +178,7 @@ class DamageTrackerTest : public testing::Test {
  protected:
   FakeImplProxy proxy_;
   TestSharedBitmapManager shared_bitmap_manager_;
+  TestTaskGraphRunner task_graph_runner_;
   FakeLayerTreeHostImpl host_impl_;
 };
 
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 7814dac..9d2be10 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -56,6 +56,7 @@ scoped_ptr<LayerTreeHost> LayerTreeHost::CreateThreaded(
     LayerTreeHostClient* client,
     SharedBitmapManager* shared_bitmap_manager,
     gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+    TaskGraphRunner* task_graph_runner,
     const LayerTreeSettings& settings,
     scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner,
@@ -63,7 +64,8 @@ scoped_ptr<LayerTreeHost> LayerTreeHost::CreateThreaded(
   DCHECK(main_task_runner.get());
   DCHECK(impl_task_runner.get());
   scoped_ptr<LayerTreeHost> layer_tree_host(new LayerTreeHost(
-      client, shared_bitmap_manager, gpu_memory_buffer_manager, settings));
+      client, shared_bitmap_manager, gpu_memory_buffer_manager,
+      task_graph_runner, settings));
   layer_tree_host->InitializeThreaded(main_task_runner,
                                       impl_task_runner,
                                       external_begin_frame_source.Pass());
@@ -75,11 +77,13 @@ scoped_ptr<LayerTreeHost> LayerTreeHost::CreateSingleThreaded(
     LayerTreeHostSingleThreadClient* single_thread_client,
     SharedBitmapManager* shared_bitmap_manager,
     gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+    TaskGraphRunner* task_graph_runner,
     const LayerTreeSettings& settings,
     scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
     scoped_ptr<BeginFrameSource> external_begin_frame_source) {
   scoped_ptr<LayerTreeHost> layer_tree_host(new LayerTreeHost(
-      client, shared_bitmap_manager, gpu_memory_buffer_manager, settings));
+      client, shared_bitmap_manager, gpu_memory_buffer_manager,
+      task_graph_runner, settings));
   layer_tree_host->InitializeSingleThreaded(single_thread_client,
                                             main_task_runner,
                                             external_begin_frame_source.Pass());
@@ -90,6 +94,7 @@ LayerTreeHost::LayerTreeHost(
     LayerTreeHostClient* client,
     SharedBitmapManager* shared_bitmap_manager,
     gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+    TaskGraphRunner* task_graph_runner,
     const LayerTreeSettings& settings)
     : micro_benchmark_controller_(this),
       next_ui_resource_id_(1),
@@ -121,6 +126,7 @@ LayerTreeHost::LayerTreeHost(
       next_commit_forces_redraw_(false),
       shared_bitmap_manager_(shared_bitmap_manager),
       gpu_memory_buffer_manager_(gpu_memory_buffer_manager),
+      task_graph_runner_(task_graph_runner),
       surface_id_namespace_(0u),
       next_surface_sequence_(1u) {
   if (settings_.accelerated_animation_enabled)
@@ -430,17 +436,14 @@ void LayerTreeHost::DidFailToInitializeOutputSurface() {
 scoped_ptr<LayerTreeHostImpl> LayerTreeHost::CreateLayerTreeHostImpl(
     LayerTreeHostImplClient* client) {
   DCHECK(proxy_->IsImplThread());
-  scoped_ptr<LayerTreeHostImpl> host_impl =
-      LayerTreeHostImpl::Create(settings_,
-                                client,
-                                proxy_.get(),
-                                rendering_stats_instrumentation_.get(),
-                                shared_bitmap_manager_,
-                                gpu_memory_buffer_manager_,
-                                id_);
+  scoped_ptr<LayerTreeHostImpl> host_impl = LayerTreeHostImpl::Create(
+      settings_, client, proxy_.get(), rendering_stats_instrumentation_.get(),
+      shared_bitmap_manager_, gpu_memory_buffer_manager_, task_graph_runner_,
+      id_);
   host_impl->SetUseGpuRasterization(UseGpuRasterization());
   shared_bitmap_manager_ = NULL;
   gpu_memory_buffer_manager_ = NULL;
+  task_graph_runner_ = NULL;
   top_controls_manager_weak_ptr_ =
       host_impl->top_controls_manager()->AsWeakPtr();
   input_handler_weak_ptr_ = host_impl->AsWeakPtr();
diff --git a/cc/trees/layer_tree_host.h b/cc/trees/layer_tree_host.h
index 1379d08..e1bcad5 100644
--- a/cc/trees/layer_tree_host.h
+++ b/cc/trees/layer_tree_host.h
@@ -61,6 +61,7 @@ class RenderingStatsInstrumentation;
 class ResourceProvider;
 class ResourceUpdateQueue;
 class SharedBitmapManager;
+class TaskGraphRunner;
 class TopControlsManager;
 class UIResourceRequest;
 struct PendingPageScaleAnimation;
@@ -75,6 +76,7 @@ class CC_EXPORT LayerTreeHost {
       LayerTreeHostClient* client,
       SharedBitmapManager* shared_bitmap_manager,
       gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+      TaskGraphRunner* task_graph_runner,
       const LayerTreeSettings& settings,
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
       scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner,
@@ -85,6 +87,7 @@ class CC_EXPORT LayerTreeHost {
       LayerTreeHostSingleThreadClient* single_thread_client,
       SharedBitmapManager* shared_bitmap_manager,
       gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+      TaskGraphRunner* task_graph_runner,
       const LayerTreeSettings& settings,
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
       scoped_ptr<BeginFrameSource> external_begin_frame_source);
@@ -307,6 +310,7 @@ class CC_EXPORT LayerTreeHost {
   LayerTreeHost(LayerTreeHostClient* client,
                 SharedBitmapManager* shared_bitmap_manager,
                 gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+                TaskGraphRunner* task_graph_runner,
                 const LayerTreeSettings& settings);
   void InitializeThreaded(
       scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
@@ -440,6 +444,7 @@ class CC_EXPORT LayerTreeHost {
 
   SharedBitmapManager* shared_bitmap_manager_;
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager_;
+  TaskGraphRunner* task_graph_runner_;
 
   ScopedPtrVector<SwapPromise> swap_promise_list_;
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
diff --git a/cc/trees/layer_tree_host_common_unittest.cc b/cc/trees/layer_tree_host_common_unittest.cc
index d18c1c8..082d14f 100644
--- a/cc/trees/layer_tree_host_common_unittest.cc
+++ b/cc/trees/layer_tree_host_common_unittest.cc
@@ -28,6 +28,7 @@
 #include "cc/test/fake_picture_layer_impl.h"
 #include "cc/test/geometry_test_utils.h"
 #include "cc/test/layer_tree_host_common_test.h"
+#include "cc/test/test_task_graph_runner.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "cc/trees/proxy.h"
 #include "cc/trees/single_thread_proxy.h"
@@ -315,7 +316,7 @@ TEST_F(LayerTreeHostCommonTest, TransformsAboutScrollOffset) {
 
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
 
   gfx::Transform identity_matrix;
   scoped_ptr<LayerImpl> sublayer_scoped_ptr(
@@ -5721,7 +5722,7 @@ TEST_F(LayerTreeHostCommonTest, TransparentChildRenderSurfaceCreation) {
 TEST_F(LayerTreeHostCommonTest, OpacityAnimatingOnPendingTree) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   scoped_ptr<LayerImpl> root = LayerImpl::Create(host_impl.pending_tree(), 1);
 
@@ -5763,7 +5764,7 @@ class LCDTextTest
       public testing::TestWithParam<LCDTextTestParam> {
  public:
   LCDTextTest()
-      : host_impl_(&proxy_, &shared_bitmap_manager_),
+      : host_impl_(&proxy_, &shared_bitmap_manager_, &task_graph_runner_),
         root_(nullptr),
         child_(nullptr),
         grand_child_(nullptr) {}
@@ -5810,6 +5811,7 @@ class LCDTextTest
 
   FakeImplProxy proxy_;
   TestSharedBitmapManager shared_bitmap_manager_;
+  TestTaskGraphRunner task_graph_runner_;
   FakeLayerTreeHostImpl host_impl_;
 
   LayerImpl* root_;
@@ -5947,7 +5949,7 @@ INSTANTIATE_TEST_CASE_P(LayerTreeHostCommonTest,
 TEST_F(LayerTreeHostCommonTest, SubtreeHidden_SingleLayer) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   const gfx::Transform identity_matrix;
 
@@ -6005,7 +6007,7 @@ TEST_F(LayerTreeHostCommonTest, SubtreeHidden_SingleLayer) {
 TEST_F(LayerTreeHostCommonTest, SubtreeHidden_SingleLayerImpl) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   const gfx::Transform identity_matrix;
 
@@ -6050,7 +6052,7 @@ TEST_F(LayerTreeHostCommonTest, SubtreeHidden_SingleLayerImpl) {
 TEST_F(LayerTreeHostCommonTest, SubtreeHidden_TwoLayers) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   const gfx::Transform identity_matrix;
 
@@ -6107,7 +6109,7 @@ TEST_F(LayerTreeHostCommonTest, SubtreeHidden_TwoLayers) {
 TEST_F(LayerTreeHostCommonTest, SubtreeHidden_TwoLayersImpl) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   const gfx::Transform identity_matrix;
 
@@ -6152,7 +6154,7 @@ void EmptyCopyOutputCallback(scoped_ptr<CopyOutputResult> result) {}
 TEST_F(LayerTreeHostCommonTest, SubtreeHiddenWithCopyRequest) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   const gfx::Transform identity_matrix;
 
@@ -6299,7 +6301,7 @@ TEST_F(LayerTreeHostCommonTest, SubtreeHiddenWithCopyRequest) {
 TEST_F(LayerTreeHostCommonTest, ClippedOutCopyRequest) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   const gfx::Transform identity_matrix;
 
@@ -6374,7 +6376,7 @@ TEST_F(LayerTreeHostCommonTest, ClippedOutCopyRequest) {
 TEST_F(LayerTreeHostCommonTest, VisibleContentRectInsideSurface) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   const gfx::Transform identity_matrix;
 
@@ -6985,7 +6987,7 @@ TEST_F(LayerTreeHostCommonTest,
 TEST_F(LayerTreeHostCommonTest, CanRenderToSeparateSurface) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   scoped_ptr<LayerImpl> root =
       LayerImpl::Create(host_impl.active_tree(), 12345);
   scoped_ptr<LayerImpl> child1 =
@@ -7706,7 +7708,7 @@ TEST_F(LayerTreeHostCommonTest, ScrollCompensationWithRounding) {
   //
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   scoped_ptr<LayerImpl> root = LayerImpl::Create(host_impl.active_tree(), 1);
   scoped_ptr<LayerImpl> container =
@@ -7850,7 +7852,7 @@ TEST_F(LayerTreeHostCommonTest,
   //
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   host_impl.CreatePendingTree();
   scoped_ptr<LayerImpl> root = LayerImpl::Create(host_impl.active_tree(), 1);
   scoped_ptr<LayerImpl> container =
@@ -7944,7 +7946,7 @@ class AnimationScaleFactorTrackingLayerImpl : public LayerImpl {
 TEST_F(LayerTreeHostCommonTest, MaximumAnimationScaleFactor) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   gfx::Transform identity_matrix;
   scoped_ptr<AnimationScaleFactorTrackingLayerImpl> grand_parent =
       AnimationScaleFactorTrackingLayerImpl::Create(host_impl.active_tree(), 1);
@@ -8161,7 +8163,7 @@ static void GatherDrawnLayers(LayerImplList* rsll,
 TEST_F(LayerTreeHostCommonTest, RenderSurfaceLayerListMembership) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
   gfx::Transform identity_matrix;
 
   scoped_ptr<LayerImpl> grand_parent =
@@ -8404,7 +8406,7 @@ TEST_F(LayerTreeHostCommonTest, RenderSurfaceLayerListMembership) {
 TEST_F(LayerTreeHostCommonTest, DrawPropertyScales) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
 
   scoped_ptr<LayerImpl> root = LayerImpl::Create(host_impl.active_tree(), 1);
   LayerImpl* root_layer = root.get();
@@ -8684,7 +8686,7 @@ TEST_F(LayerTreeHostCommonTest, VisibleContentRectInChildRenderSurface) {
 TEST_F(LayerTreeHostCommonTest, BoundsDeltaAffectVisibleContentRect) {
   FakeImplProxy proxy;
   TestSharedBitmapManager shared_bitmap_manager;
-  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager);
+  FakeLayerTreeHostImpl host_impl(&proxy, &shared_bitmap_manager, nullptr);
 
   // Set two layers: the root layer clips it's child,
   // the child draws its content.
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 9965d7a..2c13fcb 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -170,14 +170,11 @@ scoped_ptr<LayerTreeHostImpl> LayerTreeHostImpl::Create(
     RenderingStatsInstrumentation* rendering_stats_instrumentation,
     SharedBitmapManager* shared_bitmap_manager,
     gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+    TaskGraphRunner* task_graph_runner,
     int id) {
-  return make_scoped_ptr(new LayerTreeHostImpl(settings,
-                                               client,
-                                               proxy,
-                                               rendering_stats_instrumentation,
-                                               shared_bitmap_manager,
-                                               gpu_memory_buffer_manager,
-                                               id));
+  return make_scoped_ptr(new LayerTreeHostImpl(
+      settings, client, proxy, rendering_stats_instrumentation,
+      shared_bitmap_manager, gpu_memory_buffer_manager, task_graph_runner, id));
 }
 
 LayerTreeHostImpl::LayerTreeHostImpl(
@@ -187,6 +184,7 @@ LayerTreeHostImpl::LayerTreeHostImpl(
     RenderingStatsInstrumentation* rendering_stats_instrumentation,
     SharedBitmapManager* shared_bitmap_manager,
     gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+    TaskGraphRunner* task_graph_runner,
     int id)
     : client_(client),
       proxy_(proxy),
@@ -225,6 +223,7 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       micro_benchmark_controller_(this),
       shared_bitmap_manager_(shared_bitmap_manager),
       gpu_memory_buffer_manager_(gpu_memory_buffer_manager),
+      task_graph_runner_(task_graph_runner),
       id_(id),
       requires_high_res_to_draw_(false),
       is_likely_to_require_a_draw_(false),
@@ -2032,8 +2031,7 @@ void LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
         ResourcePool::Create(resource_provider_.get(), GL_TEXTURE_2D);
 
     *tile_task_worker_pool = BitmapTileTaskWorkerPool::Create(
-        task_runner, TileTaskWorkerPool::GetTaskGraphRunner(),
-        resource_provider_.get());
+        task_runner, task_graph_runner_, resource_provider_.get());
     return;
   }
 
@@ -2042,7 +2040,7 @@ void LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
         ResourcePool::Create(resource_provider_.get(), GL_TEXTURE_2D);
 
     *tile_task_worker_pool = GpuTileTaskWorkerPool::Create(
-        task_runner, TileTaskWorkerPool::GetTaskGraphRunner(),
+        task_runner, task_graph_runner_,
         static_cast<GpuRasterizer*>(rasterizer_.get()));
     return;
   }
@@ -2066,7 +2064,7 @@ void LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
         single_thread_synchronous_task_graph_runner_.reset(new TaskGraphRunner);
         task_graph_runner = single_thread_synchronous_task_graph_runner_.get();
       } else {
-        task_graph_runner = TileTaskWorkerPool::GetTaskGraphRunner();
+        task_graph_runner = task_graph_runner_;
       }
 
       *tile_task_worker_pool = ZeroCopyTileTaskWorkerPool::Create(
@@ -2082,9 +2080,8 @@ void LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
           ResourcePool::Create(resource_provider_.get(), GL_TEXTURE_2D);
 
       *tile_task_worker_pool = OneCopyTileTaskWorkerPool::Create(
-          task_runner, TileTaskWorkerPool::GetTaskGraphRunner(),
-          context_provider, resource_provider_.get(),
-          staging_resource_pool_.get());
+          task_runner, task_graph_runner_, context_provider,
+          resource_provider_.get(), staging_resource_pool_.get());
       return;
     }
   }
@@ -2098,7 +2095,7 @@ void LayerTreeHostImpl::CreateResourceAndTileTaskWorkerPool(
       resource_provider_.get(), GL_TEXTURE_2D);
 
   *tile_task_worker_pool = PixelBufferTileTaskWorkerPool::Create(
-      task_runner, TileTaskWorkerPool::GetTaskGraphRunner(), context_provider,
+      task_runner, task_graph_runner_, context_provider,
       resource_provider_.get(),
       GetMaxTransferBufferUsageBytes(context_provider->ContextCapabilities(),
                                      settings_.renderer_settings.refresh_rate));
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index b6e5903..2efe2da 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -142,6 +142,7 @@ class CC_EXPORT LayerTreeHostImpl
       RenderingStatsInstrumentation* rendering_stats_instrumentation,
       SharedBitmapManager* shared_bitmap_manager,
       gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+      TaskGraphRunner* task_graph_runner,
       int id);
   ~LayerTreeHostImpl() override;
 
@@ -531,6 +532,7 @@ class CC_EXPORT LayerTreeHostImpl
       RenderingStatsInstrumentation* rendering_stats_instrumentation,
       SharedBitmapManager* shared_bitmap_manager,
       gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager,
+      TaskGraphRunner* task_graph_runner,
       int id);
 
   // Virtual for testing.
@@ -734,6 +736,7 @@ class CC_EXPORT LayerTreeHostImpl
 
   SharedBitmapManager* shared_bitmap_manager_;
   gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager_;
+  TaskGraphRunner* task_graph_runner_;
   int id_;
 
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 1526f93..49628d1 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -54,6 +54,7 @@
 #include "cc/test/render_pass_test_common.h"
 #include "cc/test/test_gpu_memory_buffer_manager.h"
 #include "cc/test/test_shared_bitmap_manager.h"
+#include "cc/test/test_task_graph_runner.h"
 #include "cc/test/test_web_graphics_context_3d.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "cc/trees/single_thread_proxy.h"
@@ -86,6 +87,7 @@ class LayerTreeHostImplTest : public testing::Test,
         always_main_thread_blocked_(&proxy_),
         shared_bitmap_manager_(new TestSharedBitmapManager),
         gpu_memory_buffer_manager_(new TestGpuMemoryBufferManager),
+        task_graph_runner_(new TestTaskGraphRunner),
         on_can_draw_state_changed_called_(false),
         did_notify_ready_to_activate_(false),
         did_request_commit_(false),
@@ -167,13 +169,10 @@ class LayerTreeHostImplTest : public testing::Test,
 
   virtual bool CreateHostImpl(const LayerTreeSettings& settings,
                               scoped_ptr<OutputSurface> output_surface) {
-    host_impl_ = LayerTreeHostImpl::Create(settings,
-                                           this,
-                                           &proxy_,
-                                           &stats_instrumentation_,
-                                           shared_bitmap_manager_.get(),
-                                           gpu_memory_buffer_manager_.get(),
-                                           0);
+    host_impl_ = LayerTreeHostImpl::Create(
+        settings, this, &proxy_, &stats_instrumentation_,
+        shared_bitmap_manager_.get(), gpu_memory_buffer_manager_.get(),
+        task_graph_runner_.get(), 0);
     bool init = host_impl_->InitializeRenderer(output_surface.Pass());
     host_impl_->SetViewportSize(gfx::Size(10, 10));
     return init;
@@ -395,6 +394,7 @@ class LayerTreeHostImplTest : public testing::Test,
 
   scoped_ptr<TestSharedBitmapManager> shared_bitmap_manager_;
   scoped_ptr<TestGpuMemoryBufferManager> gpu_memory_buffer_manager_;
+  scoped_ptr<TestTaskGraphRunner> task_graph_runner_;
   scoped_ptr<LayerTreeHostImpl> host_impl_;
   FakeRenderingStatsInstrumentation stats_instrumentation_;
   bool on_can_draw_state_changed_called_;
@@ -1547,6 +1547,7 @@ class LayerTreeHostImplOverridePhysicalTime : public LayerTreeHostImpl {
                           rendering_stats_instrumentation,
                           manager,
                           NULL,
+                          NULL,
                           0) {}
 
   BeginFrameArgs CurrentBeginFrameArgs() const override {
@@ -5046,16 +5047,10 @@ TEST_F(LayerTreeHostImplTest, PartialSwapReceivesDamageRect) {
   // that we can force partial swap enabled.
   LayerTreeSettings settings;
   settings.renderer_settings.partial_swap_enabled = true;
-  scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
-      new TestSharedBitmapManager());
   scoped_ptr<LayerTreeHostImpl> layer_tree_host_impl =
-      LayerTreeHostImpl::Create(settings,
-                                this,
-                                &proxy_,
-                                &stats_instrumentation_,
-                                shared_bitmap_manager.get(),
-                                NULL,
-                                0);
+      LayerTreeHostImpl::Create(
+          settings, this, &proxy_, &stats_instrumentation_,
+          shared_bitmap_manager_.get(), NULL, task_graph_runner_.get(), 0);
   layer_tree_host_impl->InitializeRenderer(output_surface.Pass());
   layer_tree_host_impl->SetViewportSize(gfx::Size(500, 500));
 
@@ -5343,7 +5338,7 @@ static scoped_ptr<LayerTreeHostImpl> SetupLayersForOpacity(
   LayerTreeSettings settings;
   settings.renderer_settings.partial_swap_enabled = partial_swap;
   scoped_ptr<LayerTreeHostImpl> my_host_impl = LayerTreeHostImpl::Create(
-      settings, client, proxy, stats_instrumentation, manager, NULL, 0);
+      settings, client, proxy, stats_instrumentation, manager, NULL, NULL, 0);
   my_host_impl->InitializeRenderer(output_surface.Pass());
   my_host_impl->SetViewportSize(gfx::Size(100, 100));
 
@@ -6669,13 +6664,10 @@ TEST_F(LayerTreeHostImplTestDeferredInitialize, Fails) {
 // doesn't support memory management extensions.
 TEST_F(LayerTreeHostImplTest, DefaultMemoryAllocation) {
   LayerTreeSettings settings;
-  host_impl_ = LayerTreeHostImpl::Create(settings,
-                                         this,
-                                         &proxy_,
-                                         &stats_instrumentation_,
-                                         shared_bitmap_manager_.get(),
-                                         gpu_memory_buffer_manager_.get(),
-                                         0);
+  host_impl_ = LayerTreeHostImpl::Create(
+      settings, this, &proxy_, &stats_instrumentation_,
+      shared_bitmap_manager_.get(), gpu_memory_buffer_manager_.get(),
+      task_graph_runner_.get(), 0);
 
   scoped_ptr<OutputSurface> output_surface(
       FakeOutputSurface::Create3d(TestWebGraphicsContext3D::Create()));
@@ -6716,7 +6708,7 @@ TEST_F(LayerTreeHostImplTest, MemoryPolicy) {
   LayerTreeSettings settings;
   settings.gpu_rasterization_enabled = true;
   host_impl_ = LayerTreeHostImpl::Create(
-      settings, this, &proxy_, &stats_instrumentation_, NULL, NULL, 0);
+      settings, this, &proxy_, &stats_instrumentation_, NULL, NULL, NULL, 0);
   host_impl_->SetUseGpuRasterization(true);
   host_impl_->SetVisible(true);
   host_impl_->SetMemoryPolicy(policy1);
@@ -6779,8 +6771,9 @@ class LayerTreeHostImplTestPrepareTiles : public LayerTreeHostImplTest {
     LayerTreeSettings settings;
     settings.impl_side_painting = true;
 
-    fake_host_impl_ = new FakeLayerTreeHostImpl(
-        settings, &proxy_, shared_bitmap_manager_.get());
+    fake_host_impl_ = new FakeLayerTreeHostImpl(settings, &proxy_,
+                                                shared_bitmap_manager_.get(),
+                                                task_graph_runner_.get());
     host_impl_.reset(fake_host_impl_);
     host_impl_->InitializeRenderer(CreateOutputSurface());
     host_impl_->SetViewportSize(gfx::Size(10, 10));
diff --git a/cc/trees/layer_tree_host_unittest.cc b/cc/trees/layer_tree_host_unittest.cc
index 20ef496..415b23e 100644
--- a/cc/trees/layer_tree_host_unittest.cc
+++ b/cc/trees/layer_tree_host_unittest.cc
@@ -2209,7 +2209,7 @@ class LayerTreeHostWithProxy : public LayerTreeHost {
   LayerTreeHostWithProxy(FakeLayerTreeHostClient* client,
                          const LayerTreeSettings& settings,
                          scoped_ptr<FakeProxy> proxy)
-      : LayerTreeHost(client, NULL, NULL, settings) {
+      : LayerTreeHost(client, NULL, NULL, NULL, settings) {
     proxy->SetLayerTreeHost(this);
     client->SetLayerTreeHost(this);
     InitializeForTesting(proxy.Pass());
@@ -2281,14 +2281,9 @@ TEST(LayerTreeHostTest, PartialUpdatesWithGLRenderer) {
 
   scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
       new TestSharedBitmapManager());
-  scoped_ptr<LayerTreeHost> host =
-      LayerTreeHost::CreateSingleThreaded(&client,
-                                          &client,
-                                          shared_bitmap_manager.get(),
-                                          NULL,
-                                          settings,
-                                          base::MessageLoopProxy::current(),
-                                          nullptr);
+  scoped_ptr<LayerTreeHost> host = LayerTreeHost::CreateSingleThreaded(
+      &client, &client, shared_bitmap_manager.get(), NULL, NULL, settings,
+      base::MessageLoopProxy::current(), nullptr);
   client.SetLayerTreeHost(host.get());
   host->Composite(base::TimeTicks::Now());
 
@@ -2305,14 +2300,9 @@ TEST(LayerTreeHostTest, PartialUpdatesWithSoftwareRenderer) {
 
   scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
       new TestSharedBitmapManager());
-  scoped_ptr<LayerTreeHost> host =
-      LayerTreeHost::CreateSingleThreaded(&client,
-                                          &client,
-                                          shared_bitmap_manager.get(),
-                                          NULL,
-                                          settings,
-                                          base::MessageLoopProxy::current(),
-                                          nullptr);
+  scoped_ptr<LayerTreeHost> host = LayerTreeHost::CreateSingleThreaded(
+      &client, &client, shared_bitmap_manager.get(), NULL, NULL, settings,
+      base::MessageLoopProxy::current(), nullptr);
   client.SetLayerTreeHost(host.get());
   host->Composite(base::TimeTicks::Now());
 
@@ -2329,14 +2319,9 @@ TEST(LayerTreeHostTest, PartialUpdatesWithDelegatingRendererAndGLContent) {
 
   scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
       new TestSharedBitmapManager());
-  scoped_ptr<LayerTreeHost> host =
-      LayerTreeHost::CreateSingleThreaded(&client,
-                                          &client,
-                                          shared_bitmap_manager.get(),
-                                          NULL,
-                                          settings,
-                                          base::MessageLoopProxy::current(),
-                                          nullptr);
+  scoped_ptr<LayerTreeHost> host = LayerTreeHost::CreateSingleThreaded(
+      &client, &client, shared_bitmap_manager.get(), NULL, NULL, settings,
+      base::MessageLoopProxy::current(), nullptr);
   client.SetLayerTreeHost(host.get());
   host->Composite(base::TimeTicks::Now());
 
@@ -2354,14 +2339,9 @@ TEST(LayerTreeHostTest,
 
   scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
       new TestSharedBitmapManager());
-  scoped_ptr<LayerTreeHost> host =
-      LayerTreeHost::CreateSingleThreaded(&client,
-                                          &client,
-                                          shared_bitmap_manager.get(),
-                                          NULL,
-                                          settings,
-                                          base::MessageLoopProxy::current(),
-                                          nullptr);
+  scoped_ptr<LayerTreeHost> host = LayerTreeHost::CreateSingleThreaded(
+      &client, &client, shared_bitmap_manager.get(), NULL, NULL, settings,
+      base::MessageLoopProxy::current(), nullptr);
   client.SetLayerTreeHost(host.get());
   host->Composite(base::TimeTicks::Now());
 
diff --git a/cc/trees/layer_tree_host_unittest_no_message_loop.cc b/cc/trees/layer_tree_host_unittest_no_message_loop.cc
index 622143d..3abc4dc 100644
--- a/cc/trees/layer_tree_host_unittest_no_message_loop.cc
+++ b/cc/trees/layer_tree_host_unittest_no_message_loop.cc
@@ -106,7 +106,7 @@ class LayerTreeHostNoMessageLoopTest
     settings.verify_property_trees = true;
     settings.raster_enabled = false;
     layer_tree_host_ = LayerTreeHost::CreateSingleThreaded(
-        this, this, nullptr, nullptr, settings, nullptr, nullptr);
+        this, this, nullptr, nullptr, nullptr, settings, nullptr, nullptr);
     layer_tree_host_->SetViewportSize(size_);
     layer_tree_host_->SetRootLayer(root_layer_);
   }
diff --git a/cc/trees/layer_tree_host_unittest_scroll.cc b/cc/trees/layer_tree_host_unittest_scroll.cc
index fce09d4..be972e9 100644
--- a/cc/trees/layer_tree_host_unittest_scroll.cc
+++ b/cc/trees/layer_tree_host_unittest_scroll.cc
@@ -1126,14 +1126,10 @@ TEST(LayerTreeHostFlingTest, DidStopFlingingThread) {
   ASSERT_TRUE(impl_thread.message_loop_proxy().get());
   scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
       new TestSharedBitmapManager());
-  scoped_ptr<LayerTreeHost> layer_tree_host =
-      LayerTreeHost::CreateThreaded(&client,
-                                    shared_bitmap_manager.get(),
-                                    NULL,
-                                    settings,
-                                    base::MessageLoopProxy::current(),
-                                    impl_thread.message_loop_proxy(),
-                                    nullptr);
+  scoped_ptr<LayerTreeHost> layer_tree_host = LayerTreeHost::CreateThreaded(
+      &client, shared_bitmap_manager.get(), NULL, NULL, settings,
+      base::MessageLoopProxy::current(), impl_thread.message_loop_proxy(),
+      nullptr);
 
   impl_thread.message_loop_proxy()
       ->PostTask(FROM_HERE,
diff --git a/cc/trees/layer_tree_impl_unittest.cc b/cc/trees/layer_tree_impl_unittest.cc
index 06df3c2..c4abd52 100644
--- a/cc/trees/layer_tree_impl_unittest.cc
+++ b/cc/trees/layer_tree_impl_unittest.cc
@@ -13,6 +13,7 @@
 #include "cc/test/geometry_test_utils.h"
 #include "cc/test/layer_tree_host_common_test.h"
 #include "cc/test/test_shared_bitmap_manager.h"
+#include "cc/test/test_task_graph_runner.h"
 #include "cc/trees/layer_tree_host_impl.h"
 #include "ui/gfx/geometry/size_conversions.h"
 
@@ -25,8 +26,8 @@ class LayerTreeImplTest : public LayerTreeHostCommonTest {
     LayerTreeSettings settings;
     settings.layer_transforms_should_scale_layer_contents = true;
     settings.scrollbar_show_scale_threshold = 1.1f;
-    host_impl_.reset(
-        new FakeLayerTreeHostImpl(settings, &proxy_, &shared_bitmap_manager_));
+    host_impl_.reset(new FakeLayerTreeHostImpl(
+        settings, &proxy_, &shared_bitmap_manager_, &task_graph_runner_));
     EXPECT_TRUE(host_impl_->InitializeRenderer(FakeOutputSurface::Create3d()));
   }
 
@@ -40,6 +41,7 @@ class LayerTreeImplTest : public LayerTreeHostCommonTest {
 
  private:
   TestSharedBitmapManager shared_bitmap_manager_;
+  TestTaskGraphRunner task_graph_runner_;
   FakeImplProxy proxy_;
   scoped_ptr<FakeLayerTreeHostImpl> host_impl_;
 };
diff --git a/cc/trees/layer_tree_settings.cc b/cc/trees/layer_tree_settings.cc
index d10a141..09314adc 100644
--- a/cc/trees/layer_tree_settings.cc
+++ b/cc/trees/layer_tree_settings.cc
@@ -70,7 +70,8 @@ LayerTreeSettings::LayerTreeSettings()
       use_occlusion_for_tile_prioritization(false),
       record_full_layer(false),
       use_display_lists(false),
-      verify_property_trees(false) {
+      verify_property_trees(false),
+      gather_pixel_refs(false) {
 }
 
 LayerTreeSettings::~LayerTreeSettings() {}
diff --git a/cc/trees/layer_tree_settings.h b/cc/trees/layer_tree_settings.h
index c3dd38e5..1f61f89 100644
--- a/cc/trees/layer_tree_settings.h
+++ b/cc/trees/layer_tree_settings.h
@@ -83,6 +83,7 @@ class CC_EXPORT LayerTreeSettings {
   bool record_full_layer;
   bool use_display_lists;
   bool verify_property_trees;
+  bool gather_pixel_refs;
 
   LayerTreeDebugState initial_debug_state;
 
diff --git a/cc/trees/occlusion_tracker_perftest.cc b/cc/trees/occlusion_tracker_perftest.cc
index e53a05f..854dacd 100644
--- a/cc/trees/occlusion_tracker_perftest.cc
+++ b/cc/trees/occlusion_tracker_perftest.cc
@@ -36,13 +36,9 @@ class OcclusionTrackerPerfTest : public testing::Test {
   void CreateHost() {
     LayerTreeSettings settings;
     shared_bitmap_manager_.reset(new TestSharedBitmapManager());
-    host_impl_ = LayerTreeHostImpl::Create(settings,
-                                           &client_,
-                                           &proxy_,
-                                           &stats_,
-                                           shared_bitmap_manager_.get(),
-                                           NULL,
-                                           1);
+    host_impl_ =
+        LayerTreeHostImpl::Create(settings, &client_, &proxy_, &stats_,
+                                  shared_bitmap_manager_.get(), NULL, NULL, 1);
     host_impl_->InitializeRenderer(FakeOutputSurface::Create3d());
 
     scoped_ptr<LayerImpl> root_layer = LayerImpl::Create(active_tree(), 1);
diff --git a/cc/trees/tree_synchronizer_unittest.cc b/cc/trees/tree_synchronizer_unittest.cc
index d48f821..a17bec8 100644
--- a/cc/trees/tree_synchronizer_unittest.cc
+++ b/cc/trees/tree_synchronizer_unittest.cc
@@ -556,13 +556,8 @@ TEST_F(TreeSynchronizerTest, SynchronizeAnimations) {
   scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
       new TestSharedBitmapManager());
   scoped_ptr<LayerTreeHostImpl> host_impl =
-      LayerTreeHostImpl::Create(settings,
-                                NULL,
-                                &proxy,
-                                &stats_instrumentation,
-                                shared_bitmap_manager.get(),
-                                NULL,
-                                0);
+      LayerTreeHostImpl::Create(settings, NULL, &proxy, &stats_instrumentation,
+                                shared_bitmap_manager.get(), NULL, NULL, 0);
 
   scoped_refptr<Layer> layer_tree_root = Layer::Create();
   host_->SetRootLayer(layer_tree_root);
@@ -595,13 +590,8 @@ TEST_F(TreeSynchronizerTest, SynchronizeScrollParent) {
   scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
       new TestSharedBitmapManager());
   scoped_ptr<LayerTreeHostImpl> host_impl =
-      LayerTreeHostImpl::Create(settings,
-                                NULL,
-                                &proxy,
-                                &stats_instrumentation,
-                                shared_bitmap_manager.get(),
-                                NULL,
-                                0);
+      LayerTreeHostImpl::Create(settings, NULL, &proxy, &stats_instrumentation,
+                                shared_bitmap_manager.get(), NULL, NULL, 0);
 
   scoped_refptr<Layer> layer_tree_root = Layer::Create();
   scoped_refptr<Layer> scroll_parent = Layer::Create();
@@ -668,13 +658,8 @@ TEST_F(TreeSynchronizerTest, SynchronizeClipParent) {
   scoped_ptr<SharedBitmapManager> shared_bitmap_manager(
       new TestSharedBitmapManager());
   scoped_ptr<LayerTreeHostImpl> host_impl =
-      LayerTreeHostImpl::Create(settings,
-                                NULL,
-                                &proxy,
-                                &stats_instrumentation,
-                                shared_bitmap_manager.get(),
-                                NULL,
-                                0);
+      LayerTreeHostImpl::Create(settings, NULL, &proxy, &stats_instrumentation,
+                                shared_bitmap_manager.get(), NULL, NULL, 0);
 
   scoped_refptr<Layer> layer_tree_root = Layer::Create();
   scoped_refptr<Layer> clip_parent = Layer::Create();