Continuously request keyframes if decoding does not recover.

video/video_receive_stream.h

Index: video/video_receive_stream.h
diff --git a/video/video_receive_stream.h b/video/video_receive_stream.h
index 7a4a13e474221cc5a2f0d2a690b61746be99c085..c8eef5c46946225ab72c42f0265674f3b254c549 100644
--- a/video/video_receive_stream.h
+++ b/video/video_receive_stream.h
@@ -155,6 +155,8 @@ class VideoReceiveStream : public webrtc::VideoReceiveStream,
 
   // If we have successfully decoded any frame.
   bool frame_decoded_ = false;
+
+  int64_t last_keyframe_request_ms_ = 0;
 };
 }  // namespace internal
 }  // namespace webrtc