Standardize usage of virtual/override/final in media/

media/formats/webm/webm_content_encodings_client.h

Index: media/formats/webm/webm_content_encodings_client.h
diff --git a/media/formats/webm/webm_content_encodings_client.h b/media/formats/webm/webm_content_encodings_client.h
index 5421bbc3ec615840176ebe9c0025c728279373f2..4b1bfe03ec2691b1011f81f2dcbb44cbe6338ad3 100644
--- a/media/formats/webm/webm_content_encodings_client.h
+++ b/media/formats/webm/webm_content_encodings_client.h
@@ -23,15 +23,15 @@ typedef std::vector<ContentEncoding*> ContentEncodings;
 class MEDIA_EXPORT WebMContentEncodingsClient : public WebMParserClient {
  public:
   explicit WebMContentEncodingsClient(const LogCB& log_cb);
-  virtual ~WebMContentEncodingsClient();
+  ~WebMContentEncodingsClient() override;
 
   const ContentEncodings& content_encodings() const;
 
   // WebMParserClient methods
-  virtual WebMParserClient* OnListStart(int id) override;
-  virtual bool OnListEnd(int id) override;
-  virtual bool OnUInt(int id, int64 val) override;
-  virtual bool OnBinary(int id, const uint8* data, int size) override;
+  WebMParserClient* OnListStart(int id) override;
+  bool OnListEnd(int id) override;
+  bool OnUInt(int id, int64 val) override;
+  bool OnBinary(int id, const uint8* data, int size) override;
 
  private:
   LogCB log_cb_;