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

ppapi/proxy/video_frame_resource.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 PPAPI_PROXY_VIDEO_FRAME_RESOURCE_H_
 #define PPAPI_PROXY_VIDEO_FRAME_RESOURCE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ppapi/proxy/ppapi_proxy_export.h"
 #include "ppapi/shared_impl/media_stream_buffer.h"
 #include "ppapi/shared_impl/resource.h"
 #include "ppapi/thunk/ppb_video_frame_api.h"
 
 namespace ppapi {
 namespace proxy {
 
 class PPAPI_PROXY_EXPORT VideoFrameResource : public Resource,
                                               public thunk::PPB_VideoFrame_API {
  public:
   VideoFrameResource(PP_Instance instance,
                      int32_t index,
                      MediaStreamBuffer* buffer);
 
-  virtual ~VideoFrameResource();
+  ~VideoFrameResource() override;
 
   // PluginResource overrides:
-  virtual thunk::PPB_VideoFrame_API* AsPPB_VideoFrame_API() override;
+  thunk::PPB_VideoFrame_API* AsPPB_VideoFrame_API() override;
 
   // PPB_VideoFrame_API overrides:
-  virtual PP_TimeDelta GetTimestamp() override;
-  virtual void SetTimestamp(PP_TimeDelta timestamp) override;
-  virtual PP_VideoFrame_Format GetFormat() override;
-  virtual PP_Bool GetSize(PP_Size* size) override;
-  virtual void* GetDataBuffer() override;
-  virtual uint32_t GetDataBufferSize() override;
-  virtual MediaStreamBuffer* GetBuffer() override;
-  virtual int32_t GetBufferIndex() override;
-  virtual void Invalidate() override;
+  PP_TimeDelta GetTimestamp() override;
+  void SetTimestamp(PP_TimeDelta timestamp) override;
+  PP_VideoFrame_Format GetFormat() override;
+  PP_Bool GetSize(PP_Size* size) override;
+  void* GetDataBuffer() override;
+  uint32_t GetDataBufferSize() override;
+  MediaStreamBuffer* GetBuffer() override;
+  int32_t GetBufferIndex() override;
+  void Invalidate() override;
 
   // Frame index
   int32_t index_;
 
   MediaStreamBuffer* buffer_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoFrameResource);
 };
 
 }  // namespace proxy
 }  // namespace ppapi
 
 #endif  // PPAPI_PROXY_VIDEO_FRAME_RESOURCE_H_