Add more tracing for key frames.

R=mallinath@webrtc.org, stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/1428004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@4015 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/video_engine/vie_encoder.cc

@@ -926,6 +926,7 @@ void ViEEncoder::OnReceivedIntraFrameRequest(uint32_t ssrc) {
   // Key frame request from remote side, signal to VCM.
   WEBRTC_TRACE(webrtc::kTraceStateInfo, webrtc::kTraceVideo,
                ViEId(engine_id_, channel_id_), "%s", __FUNCTION__);
+  TRACE_EVENT0("webrtc", "OnKeyFrameRequest");
 
   int idx = 0;
   {