Add sender controlled playout delay limits

webrtc/video_frame.h

Index: webrtc/video_frame.h
diff --git a/webrtc/video_frame.h b/webrtc/video_frame.h
index 4dc3411e98ac2d218077d552d6ceb4cc52f28444..e3524b45004ac9cb964d16a809a521690d70cae8 100644
--- a/webrtc/video_frame.h
+++ b/webrtc/video_frame.h
@@ -179,6 +179,11 @@ class EncodedImage {
   bool _completeFrame = false;
   AdaptReason adapt_reason_;
   int qp_ = -1;  // Quantizer value.
+
+  // When an application indicates non-zero values here, it is taken as an
+  // indication that all future frames will be constrained with those limits
+  // until the application indicates a change again.
+  PlayoutDelay playout_delay;
 };
 
 }  // namespace webrtc