cc: Parameterize the main thread task runner

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 5a1792b63ee23307c0c4d0da60f98bd8ee06ff4f..64789d238ce458ddac8ed9fb1afc768433651ca1 100644
--- a/content/renderer/gpu/render_widget_compositor.cc
+++ b/content/renderer/gpu/render_widget_compositor.cc
@@ -525,10 +525,18 @@ void RenderWidgetCompositor::Initialize(cc::LayerTreeSettings settings) {
   }
   if (compositor_message_loop_proxy.get()) {
     layer_tree_host_ = cc::LayerTreeHost::CreateThreaded(
-        this, shared_bitmap_manager, settings, compositor_message_loop_proxy);
+        this,
+        shared_bitmap_manager,
+        settings,
+        base::MessageLoopProxy::current(),
+        compositor_message_loop_proxy);
   } else {
     layer_tree_host_ = cc::LayerTreeHost::CreateSingleThreaded(
-        this, this, shared_bitmap_manager, settings);
+        this,
+        this,
+        shared_bitmap_manager,
+        settings,
+        base::MessageLoopProxy::current());
   }
   DCHECK(layer_tree_host_);
 }