Forward the SignalFirstPacketReceived to RtpReceiver.

webrtc/api/rtpreceiver.h

Index: webrtc/api/rtpreceiver.h
diff --git a/webrtc/api/rtpreceiver.h b/webrtc/api/rtpreceiver.h
index 2e7339d4da448c60888fc0cba6f0bbfc1affd752..a8e3d37f26fcc7b730dd068f146c56462289787f 100644
--- a/webrtc/api/rtpreceiver.h
+++ b/webrtc/api/rtpreceiver.h
@@ -22,13 +22,15 @@
 #include "webrtc/api/remoteaudiosource.h"
 #include "webrtc/api/videotracksource.h"
 #include "webrtc/base/basictypes.h"
+#include "webrtc/base/sigslot.h"
 #include "webrtc/media/base/videobroadcaster.h"
 
 namespace webrtc {
 
 class AudioRtpReceiver : public ObserverInterface,
                          public AudioSourceInterface::AudioObserver,
-                         public rtc::RefCountedObject<RtpReceiverInterface> {
+                         public rtc::RefCountedObject<RtpReceiverInterface>,
+                         public sigslot::has_slots<> {
  public:
   AudioRtpReceiver(MediaStreamInterface* stream,
                    const std::string& track_id,
@@ -59,17 +61,23 @@ class AudioRtpReceiver : public ObserverInterface,
   RtpParameters GetParameters() const override;
   bool SetParameters(const RtpParameters& parameters) override;
 
+  void RegisterRtpReceiverObserver(
+      RtpReceiverObserverInterface* observer) override;
+
  private:
   void Reconfigure();
+  void onFirstAudioPacketReceived();

[pthatcher2, 2016/05/20 20:23:13]

OnFirstAudioPacketReceived()

[zhihuang1, 2016/05/24 01:01:44]

Done.

 
   const std::string id_;
   const uint32_t ssrc_;
   AudioProviderInterface* provider_;  // Set to null in Stop().
   const rtc::scoped_refptr<AudioTrackInterface> track_;
   bool cached_track_enabled_;
+  RtpReceiverObserverInterface* rtp_receiver_observer_;

[pthatcher2, 2016/05/20 20:23:14]

observer_ is probably long enough of  a name.

[zhihuang1, 2016/05/24 01:01:44]

Done.

 };
 
-class VideoRtpReceiver : public rtc::RefCountedObject<RtpReceiverInterface> {
+class VideoRtpReceiver : public rtc::RefCountedObject<RtpReceiverInterface>,
+                         public sigslot::has_slots<> {
  public:
   VideoRtpReceiver(MediaStreamInterface* stream,
                    const std::string& track_id,
@@ -95,7 +103,12 @@ class VideoRtpReceiver : public rtc::RefCountedObject<RtpReceiverInterface> {
   RtpParameters GetParameters() const override;
   bool SetParameters(const RtpParameters& parameters) override;
 
+  void RegisterRtpReceiverObserver(
+      RtpReceiverObserverInterface* observer) override;

[pthatcher2, 2016/05/20 20:23:14]

Since there is only one, we should call these "Set" instead of "Register".  And
We don't need to say 
"RtpReceiver" again.  We could just name it "SetObserver".

[zhihuang1, 2016/05/24 01:01:44]

Done.

+
  private:
+  void onFirstVideoPacketReceived();

[pthatcher2, 2016/05/20 20:23:14]

Same here

[zhihuang1, 2016/05/24 01:01:44]

Done.

+
   std::string id_;
   uint32_t ssrc_;
   VideoProviderInterface* provider_;
@@ -107,6 +120,7 @@ class VideoRtpReceiver : public rtc::RefCountedObject<RtpReceiverInterface> {
   // the VideoRtpReceiver is stopped.
   rtc::scoped_refptr<VideoTrackSource> source_;
   rtc::scoped_refptr<VideoTrackInterface> track_;
+  RtpReceiverObserverInterface* rtp_receiver_observer_;

[pthatcher2, 2016/05/20 20:23:13]

Same here

 };
 
 }  // namespace webrtc