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

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 a4bb832bf62f861b2dac8c2440d88def0291da6d..af26096083c03d17ae07222189f751904a7ca3c4 100644
--- a/media/blink/webmediaplayer_impl.h
+++ b/media/blink/webmediaplayer_impl.h
@@ -650,9 +650,7 @@ class MEDIA_BLINK_EXPORT WebMediaPlayerImpl
 
   // The maximum video keyframe distance that allows triggering background
   // playback optimizations.
-  // 10 seconds by default but can be overridden by a Finch experiment.
-  base::TimeDelta max_keyframe_distance_to_disable_background_video_ =
-      base::TimeDelta::FromSeconds(10);
+  base::TimeDelta max_keyframe_distance_to_disable_background_video_;
 
   // Whether disabled the video track as an optimization.
   bool video_track_disabled_ = false;