Added metrics for background video playback.

content/renderer/media/renderer_webmediaplayer_delegate.h

Index: content/renderer/media/renderer_webmediaplayer_delegate.h
diff --git a/content/renderer/media/renderer_webmediaplayer_delegate.h b/content/renderer/media/renderer_webmediaplayer_delegate.h
index f8c8563d347718c3bc12a8cc9228200325afb90c..4ee7734889bd7fda0a660772d7d39efb6ad8f8c4 100644
--- a/content/renderer/media/renderer_webmediaplayer_delegate.h
+++ b/content/renderer/media/renderer_webmediaplayer_delegate.h
@@ -13,6 +13,7 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/default_tick_clock.h"
+#include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "content/common/content_export.h"
 #include "content/public/renderer/render_frame_observer.h"
@@ -83,6 +84,9 @@ class CONTENT_EXPORT RendererWebMediaPlayerDelegate
   // Runs periodically to suspend idle delegates in |idle_delegate_map_|.
   void CleanupIdleDelegates();
 
+  // Setter for |is_playing_background_video_| that updates the metrics.
+  void SetIsPlayingBackgroundVideo(bool is_playing);
+
   bool has_played_media_ = false;
   IDMap<Observer> id_map_;
 
@@ -110,6 +114,9 @@ class CONTENT_EXPORT RendererWebMediaPlayerDelegate
   // foreground.
   bool is_playing_background_video_ = false;
 
+  // Keeps track of when the background video playback started for metrics.
+  base::TimeTicks background_video_playing_start_time_;
+
   // The currently playing local videos. Used to determine whether
   // OnMediaDelegatePlay() should allow the videos to play in the background or
   // not.