[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 6f0e802e5cf4f21e9ac46c5a618357e378e567a3..981c1431aaa082dd675f2e805cd4ccd6c5cefa49 100644
--- a/media/blink/webmediaplayer_impl.h
+++ b/media/blink/webmediaplayer_impl.h
@@ -244,6 +244,7 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
 
  private:
   friend class WebMediaPlayerImplTest;
+  friend class WebMediaPlayerImplBackgroundBehaviorTest;
 
   void EnableOverlay();
   void DisableOverlay();
@@ -687,6 +688,10 @@ 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);
 };