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

media/cdm/ppapi/external_clear_key/libvpx_cdm_video_decoder.h

Index: media/cdm/ppapi/external_clear_key/libvpx_cdm_video_decoder.h
diff --git a/media/cdm/ppapi/external_clear_key/libvpx_cdm_video_decoder.h b/media/cdm/ppapi/external_clear_key/libvpx_cdm_video_decoder.h
index 0ba05b9cffe0240bff96bff22aadc1930957e66f..14f8b147630e69fd1567fdcace82a463d5a81f6f 100644
--- a/media/cdm/ppapi/external_clear_key/libvpx_cdm_video_decoder.h
+++ b/media/cdm/ppapi/external_clear_key/libvpx_cdm_video_decoder.h
@@ -18,17 +18,17 @@ namespace media {
 class LibvpxCdmVideoDecoder : public CdmVideoDecoder {
  public:
   explicit LibvpxCdmVideoDecoder(CdmHost* host);
-  virtual ~LibvpxCdmVideoDecoder();
+  ~LibvpxCdmVideoDecoder() override;
 
   // CdmVideoDecoder implementation.
-  virtual bool Initialize(const cdm::VideoDecoderConfig& config) override;
-  virtual void Deinitialize() override;
-  virtual void Reset() override;
-  virtual cdm::Status DecodeFrame(const uint8_t* compressed_frame,
-                                  int32_t compressed_frame_size,
-                                  int64_t timestamp,
-                                  cdm::VideoFrame* decoded_frame) override;
-  virtual bool is_initialized() const override { return is_initialized_; }
+  bool Initialize(const cdm::VideoDecoderConfig& config) override;
+  void Deinitialize() override;
+  void Reset() override;
+  cdm::Status DecodeFrame(const uint8_t* compressed_frame,
+                          int32_t compressed_frame_size,
+                          int64_t timestamp,
+                          cdm::VideoFrame* decoded_frame) override;
+  bool is_initialized() const override { return is_initialized_; }
 
   // Returns true when |format| and |data_size| specify a supported video
   // output configuration.