[Video] MediaSession API event handlers can resume background video.

media/blink/webmediaplayer_impl.h

Index: media/blink/webmediaplayer_impl.h
diff --git a/media/blink/webmediaplayer_impl.h b/media/blink/webmediaplayer_impl.h
index 974141cb1d9d30f3779f8b24b7384528e2624401..1ab3b5cda91226078ad95e62dc63cda583751aaa 100644
--- a/media/blink/webmediaplayer_impl.h
+++ b/media/blink/webmediaplayer_impl.h
@@ -241,6 +241,7 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
 
  private:
   friend class WebMediaPlayerImplTest;
+  friend class WebMediaPlayerImplBackgroundBehaviorTest;
 
   void EnableOverlay();
   void DisableOverlay();
@@ -703,6 +704,10 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
   // Pipeline media duration overridden by tests.
   base::Optional<base::TimeDelta> pipeline_media_duration_for_test_;
 
+  // Whether the video requires a user gesture to resume after it was paused in
+  // the background. Affects the value of ShouldPauseVideoWhenHidden().
+  bool video_locked_when_paused_when_hidden_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };