Adding an experimental flag to block autoplay with sound in cross-origin iframes

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 e19736a7ecbf312614899a577d0d931039449b59..47127722d4578061e4f15c6971365a96e40b7950 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -442,6 +442,10 @@ WebPreferences RenderViewHostImpl::ComputeWebkitPrefs() {
   prefs.progress_bar_completion = GetProgressBarCompletionPolicy();
 
   prefs.use_solid_color_scrollbars = true;
+#else
+  prefs.cross_origin_media_playback_requires_user_gesture =
+      base::FeatureList::GetInstance()->IsEnabled(
+          features::kCrossOriginMediaPlaybackRequiresUserGesture);
 #endif
 
   // Handle autoplay gesture override experiment.