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

media/blink/webmediaplayer_impl.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_
 #define MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 361 matching lines @@
 
   // Returns true if the player's source is streaming.
   bool IsStreaming() const;
 
   // Return whether |pipeline_metadata_| is compatible with an overlay. This
   // is intended for android.
   bool DoesOverlaySupportMetadata() const;
 
   // 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,
   // - right after the pipeline has started (|seeking_| is used to detect the
   //   when pipeline started) if the video is hidden,
   // - right ater the pipeline has resumed if the video is hidden.
   void DisableVideoTrackIfNeeded();
 
   // Enables the video track if it was disabled before to save power.
   // Must be called when either of the following happens:
@@ skipping 260 matching lines @@
 
   // Pipeline media duration overridden by tests.
   base::Optional<base::TimeDelta> pipeline_media_duration_for_test_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_