Request keyframes more frequently on stream start/decoding error.

webrtc/video/video_receive_stream.h

Index: webrtc/video/video_receive_stream.h
diff --git a/webrtc/video/video_receive_stream.h b/webrtc/video/video_receive_stream.h
index 73549cdc514ca4d5fdd0b0bdc0a4d9ab45ea02dc..d67f68a5922dc755f889e711da0e13008836896e 100644
--- a/webrtc/video/video_receive_stream.h
+++ b/webrtc/video/video_receive_stream.h
@@ -144,6 +144,10 @@ class VideoReceiveStream : public webrtc::VideoReceiveStream,
 
   std::unique_ptr<RtpStreamReceiverInterface> media_receiver_;
   std::unique_ptr<RtpStreamReceiverInterface> rtx_receiver_;
+
+  // Whenever we are in an undecodable state (stream has just started or due to
+  // a decoding error) we require a keyframe to restart the stream.
+  bool keyframe_required_ = true;
 };
 }  // namespace internal
 }  // namespace webrtc