Disable background video track behind a feature flag

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 a0f34b66f7d98c3db9ead41896275692cb19d157..8dedbf24423df912cd92606ba771bed1bb4e220f 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -81,6 +81,7 @@
 #include "content/public/common/result_codes.h"
 #include "content/public/common/url_constants.h"
 #include "content/public/common/url_utils.h"
+#include "media/base/media_switches.h"
 #include "net/base/filename_util.h"
 #include "net/base/url_util.h"
 #include "net/url_request/url_request_context_getter.h"
@@ -584,6 +585,9 @@ WebPreferences RenderViewHostImpl::ComputeWebkitPrefs() {
   if (delegate_ && delegate_->HideDownloadUI())
     prefs.hide_download_ui = true;
 
+  prefs.background_video_track_optimization_enabled =
+      base::FeatureList::IsEnabled(media::kBackgroundVideoTrackOptimization);
+
   std::map<std::string, std::string> expensive_background_throttling_prefs;
   variations::GetVariationParamsByFeature(
       features::kExpensiveBackgroundTimerThrottling,