Revert of Add a flags field to video timing extension.

webrtc/modules/rtp_rtcp/source/rtp_receiver_video.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_receiver_video.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_receiver_video.cc b/webrtc/modules/rtp_rtcp/source/rtp_receiver_video.cc
index 106f0560751d35a4e86fb72b78476a4baa428cee..845e7ac496ccb13e124c71eabba7a8844a2f3914 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_receiver_video.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_receiver_video.cc
@@ -91,7 +91,7 @@
   rtp_header->type = parsed_payload.type;
   rtp_header->type.Video.rotation = kVideoRotation_0;
   rtp_header->type.Video.content_type = VideoContentType::UNSPECIFIED;
-  rtp_header->type.Video.video_timing.flags = TimingFrameFlags::kInvalid;
+  rtp_header->type.Video.video_timing.is_timing_frame = false;
 
   // Retrieve the video rotation information.
   if (rtp_header->header.extension.hasVideoRotation) {
@@ -107,6 +107,7 @@
   if (rtp_header->header.extension.has_video_timing) {
     rtp_header->type.Video.video_timing =
         rtp_header->header.extension.video_timing;
+    rtp_header->type.Video.video_timing.is_timing_frame = true;
   }
 
   rtp_header->type.Video.playout_delay =