[Media] Plumb a feature parameter for the background video keyframe distance.

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 160 matching lines @@
                                          unsigned int texture,
                                          bool premultiply_alpha,
                                          bool flip_y) override;
 
   blink::WebAudioSourceProvider* getAudioSourceProvider() override;
 
   void setContentDecryptionModule(
       blink::WebContentDecryptionModule* cdm,
       blink::WebContentDecryptionModuleResult result) override;
 
+  void SetMaxKeyframeDistanceToDisableBackgroundVideo(base::TimeDelta distance);
+
   void SetEnableFullscreenOverlays(bool enable_overlays);
   bool supportsOverlayFullscreenVideo() override;
   void enteredFullscreen() override;
   void exitedFullscreen() override;
   void becameDominantVisibleContent(bool isDominant) override;
 
   void setPoster(const blink::WebURL& poster) override;
 
   // WebMediaPlayerDelegate::Observer implementation.
   void OnHidden() override;
@@ skipping 454 matching lines @@
 
   // Pipeline statistics overridden by tests.
   base::Optional<PipelineStatistics> pipeline_statistics_for_test_;
 
   DISALLOW_COPY_AND_ASSIGN(WebMediaPlayerImpl);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BLINK_WEBMEDIAPLAYER_IMPL_H_