Revert of Fix the video buffer size should take rtt into consideration

webrtc/modules/video_coding/frame_buffer2.h

Index: webrtc/modules/video_coding/frame_buffer2.h
diff --git a/webrtc/modules/video_coding/frame_buffer2.h b/webrtc/modules/video_coding/frame_buffer2.h
index 8de0680ef9b9a8277e88fa33cc7e02eefa44de14..13dd341aaae5b91f8bdd6ef74e901e224137e264 100644
--- a/webrtc/modules/video_coding/frame_buffer2.h
+++ b/webrtc/modules/video_coding/frame_buffer2.h
@@ -74,9 +74,6 @@ class FrameBuffer {
   // return immediately.
   void Stop();
 
-  // Updates the RTT for jitter buffer estimation.
-  void UpdateRtt(int64_t rtt_ms);
-
  private:
   struct FrameKey {
     FrameKey() : picture_id(0), spatial_layer(0) {}