Standardize usage of virtual/override/final in media/

media/blink/buffered_data_source.h

Index: media/blink/buffered_data_source.h
diff --git a/media/blink/buffered_data_source.h b/media/blink/buffered_data_source.h
index 5d2cd666347be5381f3a4a45c20cbf03186e71ff..a3eabe85c2ebce4d5b42851c16bd41b4911a5abf 100644
--- a/media/blink/buffered_data_source.h
+++ b/media/blink/buffered_data_source.h
@@ -70,7 +70,7 @@ class MEDIA_EXPORT BufferedDataSource : public DataSource {
       MediaLog* media_log,
       BufferedDataSourceHost* host,
       const DownloadingCB& downloading_cb);
-  virtual ~BufferedDataSource();
+  ~BufferedDataSource() override;
 
   // Executes |init_cb| with the result of initialization when it has completed.
   //
@@ -108,13 +108,15 @@ class MEDIA_EXPORT BufferedDataSource : public DataSource {
 
   // DataSource implementation.
   // Called from demuxer thread.
-  virtual void Stop() override;
-
-  virtual void Read(int64 position, int size, uint8* data,
-                    const DataSource::ReadCB& read_cb) override;
-  virtual bool GetSize(int64* size_out) override;
-  virtual bool IsStreaming() override;
-  virtual void SetBitrate(int bitrate) override;
+  void Stop() override;
+
+  void Read(int64 position,
+            int size,
+            uint8* data,
+            const DataSource::ReadCB& read_cb) override;
+  bool GetSize(int64* size_out) override;
+  bool IsStreaming() override;
+  void SetBitrate(int bitrate) override;
 
  protected:
   // A factory method to create a BufferedResourceLoader based on the read