Request keyframe if the first received frame is not a keyframe.

webrtc/video/rtp_stream_receiver.h

Index: webrtc/video/rtp_stream_receiver.h
diff --git a/webrtc/video/rtp_stream_receiver.h b/webrtc/video/rtp_stream_receiver.h
index afd19a7addc34a639bb5fe195c79716c950b01b5..89fc4f6b9347a41e498edc19e31f89c8b86ff7ab 100644
--- a/webrtc/video/rtp_stream_receiver.h
+++ b/webrtc/video/rtp_stream_receiver.h
@@ -192,6 +192,8 @@ class RtpStreamReceiver : public RtpData,
   // Maps a payload type to a map of out-of-band supplied codec parameters.
   std::map<uint8_t, std::map<std::string, std::string>> pt_codec_params_;
   int16_t last_payload_type_ = -1;
+
+  bool has_received_frame_;
 };
 
 }  // namespace webrtc