VCM: Adding API for the size(duration) of the jitter buffer.

Refers to the duration in time of the frames which are ready to be sent to the decoder.

Review URL: https://webrtc-codereview.appspot.com/1319004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3903 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/video_coding/main/source/receiver.cc

@@ -432,6 +432,10 @@ int VCMReceiver::SetMinReceiverDelay(int desired_delay_ms) {
   return 0;
 }
 
+int VCMReceiver::RenderBufferSizeMs() {
+  return jitter_buffer_.RenderBufferSizeMs();
+}
+
 void VCMReceiver::UpdateState(VCMReceiverState new_state) {
   CriticalSectionScoped cs(crit_sect_);
   assert(!(state_ == kPassive && new_state == kWaitForPrimaryDecode));