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

media/blink/webmediaplayer_impl.cc

Index: media/blink/webmediaplayer_impl.cc
diff --git a/media/blink/webmediaplayer_impl.cc b/media/blink/webmediaplayer_impl.cc
index b0e7d1c71f3d6819338ed00105d809ee43f03bf3..b38ce354f8d2d1809f059e6b751251e7befdbcde 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -2149,6 +2149,11 @@ void WebMediaPlayerImpl::DisableVideoTrackIfNeeded() {
   }
 }
 
+void WebMediaPlayerImpl::SetMaxKeyframeDistanceToDisableBackgroundVideo(
+    base::TimeDelta distance) {
+  max_keyframe_distance_to_disable_background_video_ = distance;
+}
+
 void WebMediaPlayerImpl::SetPipelineStatisticsForTest(
     const PipelineStatistics& stats) {
   pipeline_statistics_for_test_ = base::make_optional(stats);