[exp] cc: Introduce cc::CompositorMutator.

content/test/fake_compositor_dependencies.h

 // 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.
 
 #ifndef CONTENT_TEST_FAKE_COMPOSITOR_DEPENDENCIES_H_
 #define CONTENT_TEST_FAKE_COMPOSITOR_DEPENDENCIES_H_
 
 #include "cc/test/test_gpu_memory_buffer_manager.h"
 #include "cc/test/test_shared_bitmap_manager.h"
 #include "content/renderer/gpu/compositor_dependencies.h"
@@ skipping 17 matching lines @@
   bool IsOneCopyEnabled() override;
   bool IsElasticOverscrollEnabled() override;
   bool UseSingleThreadScheduler() override;
   uint32 GetImageTextureTarget() override;
   scoped_refptr<base::SingleThreadTaskRunner>
   GetCompositorMainThreadTaskRunner() override;
   scoped_refptr<base::SingleThreadTaskRunner>
   GetCompositorImplThreadTaskRunner() override;
   cc::SharedBitmapManager* GetSharedBitmapManager() override;
   gpu::GpuMemoryBufferManager* GetGpuMemoryBufferManager() override;
+  cc::CompositorMutator* GetCompositorMutator() override;
   RendererScheduler* GetRendererScheduler() override;
   cc::ContextProvider* GetSharedMainThreadContextProvider() override;
   scoped_ptr<cc::BeginFrameSource> CreateExternalBeginFrameSource(
       int routing_id) override;
 
   void set_use_single_thread_scheduler(bool use) {
     use_single_thread_scheduler_ = use;
   }
 
  private:
   cc::TestSharedBitmapManager shared_bitmap_manager_;
   cc::TestGpuMemoryBufferManager gpu_memory_buffer_manager_;
   FakeRendererScheduler renderer_scheduler_;
   bool use_single_thread_scheduler_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeCompositorDependencies);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_TEST_FAKE_COMPOSITOR_DEPENDENCIES_H_