Added log messages for important call setup events: first packet sent/received

webrtc/modules/video_coding/video_receiver.cc

Index: webrtc/modules/video_coding/video_receiver.cc
diff --git a/webrtc/modules/video_coding/video_receiver.cc b/webrtc/modules/video_coding/video_receiver.cc
index 5aadcf91e0eb41a1f3ed8b244db7c0de9d186f77..1bbaf7f5b2e557b2ab71483c4bd98fe362bb4494 100644
--- a/webrtc/modules/video_coding/video_receiver.cc
+++ b/webrtc/modules/video_coding/video_receiver.cc
@@ -323,6 +323,12 @@ int32_t VideoReceiver::Decode(uint16_t maxWaitTimeMs) {
     }
   }
 #endif
+
+  if (first_frame_received_()) {

[skvlad, 2016/03/26 02:00:08]

This is the only place in this CL where the OneTimeEvent is accessed while
holding a critical section, and where the thread-unsafe version can be used.

+    LOG(LS_INFO) << "Received first decodable video frame, complete = "
+                 << (frame->Complete() ? "true" : "false");
+  }
+
   const int32_t ret = Decode(*frame);
   _receiver.ReleaseFrame(frame);
   return ret;