Update {virtual,override} to follow C++11 style in media.

media/renderers/mock_gpu_video_accelerator_factories.h

Index: media/renderers/mock_gpu_video_accelerator_factories.h
diff --git a/media/renderers/mock_gpu_video_accelerator_factories.h b/media/renderers/mock_gpu_video_accelerator_factories.h
index 12a80953e93de3ea2f193eebf586651ef6da9032..9bbbb89b0c4811a024eb0e6c029fadc53d0dc9b6 100644
--- a/media/renderers/mock_gpu_video_accelerator_factories.h
+++ b/media/renderers/mock_gpu_video_accelerator_factories.h
@@ -46,14 +46,12 @@ class MockGpuVideoAcceleratorFactories : public GpuVideoAcceleratorFactories {
 
   scoped_ptr<base::SharedMemory> CreateSharedMemory(size_t size) override;
 
-  virtual scoped_ptr<VideoDecodeAccelerator> CreateVideoDecodeAccelerator()
-      override;
+  scoped_ptr<VideoDecodeAccelerator> CreateVideoDecodeAccelerator() override;
 
-  virtual scoped_ptr<VideoEncodeAccelerator> CreateVideoEncodeAccelerator()
-      override;
+  scoped_ptr<VideoEncodeAccelerator> CreateVideoEncodeAccelerator() override;
 
  private:
-  virtual ~MockGpuVideoAcceleratorFactories();
+  ~MockGpuVideoAcceleratorFactories() override;
 
   DISALLOW_COPY_AND_ASSIGN(MockGpuVideoAcceleratorFactories);
 };