MacViews: Make window content views layer-backed.

ui/views/cocoa/bridged_native_widget.mm

Index: ui/views/cocoa/bridged_native_widget.mm
diff --git a/ui/views/cocoa/bridged_native_widget.mm b/ui/views/cocoa/bridged_native_widget.mm
index 25df35a27e9d9599f25bf02c65eafb437c60b3c4..e9317173bdf40b7b684f3d93373ecf7a69a1f7e0 100644
--- a/ui/views/cocoa/bridged_native_widget.mm
+++ b/ui/views/cocoa/bridged_native_widget.mm
@@ -546,6 +546,7 @@ void BridgedNativeWidget::SetRootView(views::View* view) {
     // this should be treated as an error and caught early.
     CHECK(bridged_view_);
   }
+  [bridged_view_ setWantsLayer:YES];
   [window_ setContentView:bridged_view_];
 }
 
@@ -1267,7 +1268,8 @@ void BridgedNativeWidget::CreateCompositor() {
   ui::ContextFactoryPrivate* context_factory_private =
       ViewsDelegate::GetInstance()->GetContextFactoryPrivate();
 
-  AddCompositorSuperview();
+  //AddCompositorSuperview();
+  compositor_superview_.reset([bridged_view_ retain]);
 
   compositor_widget_.reset(new ui::AcceleratedWidgetMac());
   compositor_.reset(new ui::Compositor(context_factory, context_factory_private,