Revert of Revert of Forward input and compositing tasks to the Blink scheduler

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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 "content/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 497 matching lines @@
 }
 
 bool RenderWidgetCompositor::SendMessageToMicroBenchmark(
     int id,
     scoped_ptr<base::Value> value) {
   return layer_tree_host_->SendMessageToMicroBenchmark(id, value.Pass());
 }
 
 void RenderWidgetCompositor::Initialize(cc::LayerTreeSettings settings) {
   scoped_refptr<base::MessageLoopProxy> compositor_message_loop_proxy;
+  scoped_refptr<base::SingleThreadTaskRunner>
+      main_thread_compositor_task_runner(base::MessageLoopProxy::current());
   RenderThreadImpl* render_thread = RenderThreadImpl::current();
   cc::SharedBitmapManager* shared_bitmap_manager = NULL;
   // render_thread may be NULL in tests.
   if (render_thread) {
     compositor_message_loop_proxy =
         render_thread->compositor_message_loop_proxy();
     shared_bitmap_manager = render_thread->shared_bitmap_manager();
+    main_thread_compositor_task_runner =
+        render_thread->main_thread_compositor_task_runner();
   }
   if (compositor_message_loop_proxy.get()) {
-    layer_tree_host_ = cc::LayerTreeHost::CreateThreaded(
-        this,
-        shared_bitmap_manager,
-        settings,
-        base::MessageLoopProxy::current(),
-        compositor_message_loop_proxy);
+    layer_tree_host_ =
+        cc::LayerTreeHost::CreateThreaded(this,
+                                          shared_bitmap_manager,
+                                          settings,
+                                          main_thread_compositor_task_runner,
+                                          compositor_message_loop_proxy);
   } else {
     layer_tree_host_ = cc::LayerTreeHost::CreateSingleThreaded(
         this,
         this,
         shared_bitmap_manager,
         settings,
-        base::MessageLoopProxy::current());
+        main_thread_compositor_task_runner);
   }
   DCHECK(layer_tree_host_);
 }
 
 void RenderWidgetCompositor::setSurfaceReady() {
   // In tests without a RenderThreadImpl, don't set ready as this kicks
   // off creating output surfaces that the test can't create.
   if (RenderThreadImpl::current())
     layer_tree_host_->SetLayerTreeHostClientReady();
 }
@@ skipping 275 matching lines @@
   widget_->OnSwapBuffersAborted();
 }
 
 void RenderWidgetCompositor::RateLimitSharedMainThreadContext() {
   cc::ContextProvider* provider =
       RenderThreadImpl::current()->SharedMainThreadContextProvider().get();
   provider->ContextGL()->RateLimitOffscreenContextCHROMIUM();
 }
 
 }  // namespace content