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

content/public/common/web_preferences.h

 // Copyright 2014 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 CONTENT_PUBLIC_COMMON_WEB_PREFERENCES_H_
 #define CONTENT_PUBLIC_COMMON_WEB_PREFERENCES_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/strings/string16.h"
+#include "base/time/time.h"
 #include "build/build_config.h"
 #include "content/common/content_export.h"
 #include "ui/base/touch/touch_device.h"
 #include "url/gurl.h"
 
 namespace blink {
 class WebView;
 }
 
 namespace content {
@@ skipping 234 matching lines @@
   // in WebSettings.
   float default_minimum_page_scale_factor;
   float default_maximum_page_scale_factor;
 
   // Whether download UI should be hidden on this page.
   bool hide_download_ui;
 
   // If enabled, disabled video track when the video is in the background.
   bool background_video_track_optimization_enabled;
 
+  // If background video track optimization is enabled, don't disable video
+  // track for videos with the average keyframe distance greater than this
+  // value.
+  // TODO(avayvod, asvitkine): Query the value directly when it is available in
+  // the renderer process. See https://crbug.com/681160.
+  base::TimeDelta max_keyframe_distance_to_disable_background_video;
+
   // Whether it is a presentation receiver.
   bool presentation_receiver;
 
   // We try to keep the default values the same as the default values in
   // chrome, except for the cases where it would require lots of extra work for
   // the embedder to use the same default value.
   WebPreferences();
   WebPreferences(const WebPreferences& other);
   ~WebPreferences();
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_WEB_PREFERENCES_H_