Use FFmpeg's reordered_opaque for presentation timestamp reordering.

media/base/video_frame.cc

Index: media/base/video_frame.cc
diff --git a/media/base/video_frame.cc b/media/base/video_frame.cc
index 6767ee42fdb01de7dd8ea5685430bc5d2903a5b9..0b8239c3cc469dce495c9440de7f43f527edb829 100644
--- a/media/base/video_frame.cc
+++ b/media/base/video_frame.cc
@@ -152,7 +152,6 @@ VideoFrame::VideoFrame(VideoFrame::Format format,
   width_ = width;
   height_ = height;
   planes_ = 0;
-  repeat_count_ = 0;
   memset(&strides_, 0, sizeof(strides_));
   memset(&data_, 0, sizeof(data_));
 }