[Video] Don't pause video-only elements if they're already paused...

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 af26096083c03d17ae07222189f751904a7ca3c4..15130dea85a50ce4525df335b3717fed2b4df3fa 100644
--- a/media/blink/webmediaplayer_impl.h
+++ b/media/blink/webmediaplayer_impl.h
@@ -379,17 +379,34 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
 
   // Whether the video should be paused when hidden. Uses metadata so has
   // meaning only after the pipeline has started, otherwise returns false.
+  // Doesn't check if the video can actually be paused depending on the
+  // pipeline's state.
   bool ShouldPauseVideoWhenHidden() const;
 
   // Whether the video track should be disabled when hidden. Uses metadata so
   // has meaning only after the pipeline has started, otherwise returns false.
+  // Doesn't check if the video track can actually be disabled depending on the
+  // pipeline's state.
   bool ShouldDisableVideoWhenHidden() const;
 
   // Whether the video is suitable for background playback optimizations (either
   // pausing it or disabling the video track). Uses metadata so has meaning only
   // after the pipeline has started, otherwise returns false.
+  // The logical OR between the two methods above that is also used as their
+  // common implementation.
   bool IsBackgroundOptimizationCandidate() const;
 
+  // If enabling or disabling background video optimization has been delayed,
+  // because of the pipeline not running, seeking or resuming, this method
+  // needs to be called to update the optimization state.
+  void UpdateBackgroundVideoOptimizationState();
+
+  // Pauses a hidden video only player to save power if possible.
+  // Must be called when either of the following happens:
+  // - right after the video was hidden,
+  // - right ater the pipeline has resumed if the video is hidden.
+  void PauseVideoIfNeeded();
+
   // Disables the video track to save power if possible.
   // Must be called when either of the following happens:
   // - right after the video was hidden,