Add a command-line flag to enable threaded GPU rasterization.

content/test/fake_compositor_dependencies.cc

 // Copyright 2014 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/test/fake_compositor_dependencies.h"
 
 #include "base/message_loop/message_loop_proxy.h"
 #include "cc/test/fake_external_begin_frame_source.h"
 #include "third_party/khronos/GLES2/gl2.h"
 
@@ skipping 36 matching lines @@
 }
 
 bool FakeCompositorDependencies::IsElasticOverscrollEnabled() {
   return false;
 }
 
 bool FakeCompositorDependencies::UseSingleThreadScheduler() {
   return use_single_thread_scheduler_;
 }
 
+bool FakeCompositorDependencies::IsThreadedGpuRasterizationEnabled() {
+  return false;
+}
+
 uint32 FakeCompositorDependencies::GetImageTextureTarget() {
   return GL_TEXTURE_2D;
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
 FakeCompositorDependencies::GetCompositorMainThreadTaskRunner() {
   return base::MessageLoopProxy::current();
 }
 
 scoped_refptr<base::SingleThreadTaskRunner>
@@ skipping 20 matching lines @@
   return nullptr;
 }
 
 scoped_ptr<cc::BeginFrameSource>
 FakeCompositorDependencies::CreateExternalBeginFrameSource(int routing_id) {
   double refresh_rate = 200.0;
   return make_scoped_ptr(new cc::FakeExternalBeginFrameSource(refresh_rate));
 }
 
 }  // namespace content