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

content/browser/renderer_host/render_view_host_impl.cc

Index: content/browser/renderer_host/render_view_host_impl.cc
diff --git a/content/browser/renderer_host/render_view_host_impl.cc b/content/browser/renderer_host/render_view_host_impl.cc
index 3a1a11e203039e28b49277e21e54c1263fad6d7c..10fb3cd58d9ea2d6bf4a2ccafe87471a4770da7a 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -540,6 +540,11 @@ WebPreferences RenderViewHostImpl::ComputeWebkitPrefs() {
 
   prefs.background_video_track_optimization_enabled =
       base::FeatureList::IsEnabled(media::kBackgroundVideoTrackOptimization);
+  prefs.max_keyframe_distance_to_disable_background_video_sec =
+      variations::GetVariationParamByFeatureAsInt(
+          media::kBackgroundVideoTrackOptimization,
+          "max_keyframe_distance_sec",
+          prefs.max_keyframe_distance_to_disable_background_video_sec);
 
   std::map<std::string, std::string> expensive_background_throttling_prefs;
   variations::GetVariationParamsByFeature(