Use external begin frames in the renderer for mus

content/renderer/gpu/render_widget_compositor.cc

Index: content/renderer/gpu/render_widget_compositor.cc
diff --git a/content/renderer/gpu/render_widget_compositor.cc b/content/renderer/gpu/render_widget_compositor.cc
index 9aed1cfadca523e1f983fd21db2151ee8b38b7a3..82e555b9d7e8d5d0914c39327709519759033985 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -512,8 +512,7 @@ cc::LayerTreeSettings RenderWidgetCompositor::GenerateLayerTreeSettings(
   settings.use_cached_picture_raster =
       !cmd.HasSwitch(cc::switches::kDisableCachedPictureRaster);
 
-  if (cmd.HasSwitch(switches::kUseRemoteCompositing) ||
-      cmd.HasSwitch(switches::kIsRunningInMash))
+  if (cmd.HasSwitch(switches::kUseRemoteCompositing))
     settings.use_external_begin_frame_source = false;
 
   return settings;