Add UMA for droppedframes count

media/base/pipeline.cc

Index: media/base/pipeline.cc
diff --git a/media/base/pipeline.cc b/media/base/pipeline.cc
index 41eeb98d8a1dc85fb8e845815f2a60cf8372451e..c1b11f5e8f6b1098c49022b1971f55b869f41207 100644
--- a/media/base/pipeline.cc
+++ b/media/base/pipeline.cc
@@ -526,6 +526,10 @@ void Pipeline::StopTask(const base::Closure& stop_cb) {
   if (state_ == kStopping)
     return;
 
+  PipelineStatistics stats = GetStatistics();
+  if (renderer_ && renderer_->HasVideo() && stats.video_frames_decoded > 0)
+    UMA_HISTOGRAM_COUNTS("Media.DroppedFrameCount", stats.video_frames_dropped);
+
   SetState(kStopping);
   pending_callbacks_.reset();
   DoStop(base::Bind(&Pipeline::OnStopCompleted, weak_factory_.GetWeakPtr()));