Reland of Bug Fix: Data Race For WebMediaPlayerMS' Frame Count Variable

content/renderer/media/webmediaplayer_ms_compositor.cc

Index: content/renderer/media/webmediaplayer_ms_compositor.cc
diff --git a/content/renderer/media/webmediaplayer_ms_compositor.cc b/content/renderer/media/webmediaplayer_ms_compositor.cc
index b6d25aff45a3ae86994c7dbf8a09a5bb659694e0..7d565e18a50bfdeb00e8a25fa886e078b59d58ee 100644
--- a/content/renderer/media/webmediaplayer_ms_compositor.cc
+++ b/content/renderer/media/webmediaplayer_ms_compositor.cc
@@ -178,13 +178,15 @@
   return current_frame_.get() ? current_frame_->timestamp() : base::TimeDelta();
 }
 
-size_t WebMediaPlayerMSCompositor::total_frame_count() const {
+size_t WebMediaPlayerMSCompositor::total_frame_count() {
+  base::AutoLock auto_lock(current_frame_lock_);
   DVLOG(1) << __func__ << ", " << total_frame_count_;
   DCHECK(thread_checker_.CalledOnValidThread());
   return total_frame_count_;
 }
 
-size_t WebMediaPlayerMSCompositor::dropped_frame_count() const {
+size_t WebMediaPlayerMSCompositor::dropped_frame_count() {
+  base::AutoLock auto_lock(current_frame_lock_);
   DVLOG(1) << __func__ << ", " << dropped_frame_count_;
   DCHECK(thread_checker_.CalledOnValidThread());
   return dropped_frame_count_;