Rename VideoFrame::{Get,Set}Timestamp() to {set_}timestamp().

media/base/video_frame.h

Index: media/base/video_frame.h
diff --git a/media/base/video_frame.h b/media/base/video_frame.h
index aa9c07810e61bbf1da171bfeaec19e73a18ab914..8106a2707ff24df478c74f60a38af31cca2fd9d8 100644
--- a/media/base/video_frame.h
+++ b/media/base/video_frame.h
@@ -212,10 +212,10 @@ class MEDIA_EXPORT VideoFrame : public base::RefCountedThreadSafe<VideoFrame> {
   // Returns true if this VideoFrame represents the end of the stream.
   bool end_of_stream() const { return end_of_stream_; }
 
-  base::TimeDelta GetTimestamp() const {
+  base::TimeDelta timestamp() const {
     return timestamp_;
   }
-  void SetTimestamp(const base::TimeDelta& timestamp) {
+  void set_timestamp(const base::TimeDelta& timestamp) {
     timestamp_ = timestamp;
   }