Fix data race in VCMTiming::ResetDecodeTime.

Also thread annotating class.

BUG=
R=stefan@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/17939004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6653 4adac7df-926f-26a2-2b94-8c16560cd09d

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

@@ -58,6 +58,7 @@ void VCMTiming::Reset() {
 }
 
 void VCMTiming::ResetDecodeTime() {
+  CriticalSectionScoped lock(crit_sect_);
   codec_timer_.Reset();
 }