Reland of Make cricket::VideoFrame inherit webrtc::VideoFrame.

webrtc/video_frame.h

Index: webrtc/video_frame.h
diff --git a/webrtc/video_frame.h b/webrtc/video_frame.h
index 21654d95e4fe512df08f48c1ccf4a9992cb4b2cd..a3057e9be5df72b19928f2dc6f620ab081d5f93b 100644
--- a/webrtc/video_frame.h
+++ b/webrtc/video_frame.h
@@ -106,6 +106,10 @@ class VideoFrame {
   // Get frame timestamp (90kHz).
   uint32_t timestamp() const { return timestamp_rtp_; }
 
+  // For now, transport_frame_id and rtp timestamp are the same.
+  // TODO(nisse): Must be handled differently for QUIC.
+  uint32_t transport_frame_id() const { return timestamp(); }
+
   // Set capture ntp time in milliseconds.
   void set_ntp_time_ms(int64_t ntp_time_ms) {
     ntp_time_ms_ = ntp_time_ms;