Implement timing frames.

webrtc/common_types.h

Index: webrtc/common_types.h
diff --git a/webrtc/common_types.h b/webrtc/common_types.h
index 424afd91397414a18c6f8d96e45da4d4a73f36db..f52cab7c3f1325a826a9460e80bd094bd2f10af4 100644
--- a/webrtc/common_types.h
+++ b/webrtc/common_types.h
@@ -20,6 +20,7 @@
 
 #include "webrtc/api/video/video_content_type.h"
 #include "webrtc/api/video/video_rotation.h"
+#include "webrtc/api/video/video_timing.h"
 #include "webrtc/base/array_view.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/optional.h"
@@ -588,6 +589,10 @@ class VideoCodec {
   VideoCodecMode mode;
   bool expect_encode_from_texture;
 
+  // Timing frames configuration.

[sprang_webrtc, 2017/05/31 11:12:54]

I think you can expand this comment; it's not obvious to me what these values
will do.

[ilnik, 2017/05/31 15:17:45]

Done.

+  int64_t timingFramesDelayMs;
+  size_t minFrameSizeToForceTimingFrameBytes;

[sprang_webrtc, 2017/05/31 11:12:54]

Thinking some more on this, not sure bytes is the right type, as a frame being
"large" is a function of the current bitrate and framerate.
Maybe it can be a factor of the ideal frame size instead?

[sprang_webrtc, 2017/05/31 11:12:55]

Maybe we can make these a named struct, since they seem to be passed around as a
pair. Something like TimingFrameTriggerThresholds or so, then you could simple
name the members delay_ms and min_frame_size_bytes?
Up to you. 

[ilnik, 2017/05/31 15:17:45]

Nice idea. Done.

[ilnik, 2017/05/31 15:17:45]

Done.

+
   bool operator==(const VideoCodec& other) const = delete;
   bool operator!=(const VideoCodec& other) const = delete;
 
@@ -761,6 +766,9 @@ struct RTPHeaderExtension {
   bool hasVideoContentType;
   VideoContentType videoContentType;
 
+  bool hasVideoTiming;
+  VideoTiming videoTiming;
+
   PlayoutDelay playout_delay = {-1, -1};
 
   // For identification of a stream when ssrc is not signaled. See