MacViews: Implement non-client frame view

ui/views/widget/native_widget_mac.mm

Index: ui/views/widget/native_widget_mac.mm
diff --git a/ui/views/widget/native_widget_mac.mm b/ui/views/widget/native_widget_mac.mm
index 20db395761ee684482da88635be05860871c89e4..c06aefdba21a85a699b699c5db710bdaa582df2c 100644
--- a/ui/views/widget/native_widget_mac.mm
+++ b/ui/views/widget/native_widget_mac.mm
@@ -129,9 +129,9 @@ bool NativeWidgetMac::ShouldUseNativeFrame() const {
 }
 
 bool NativeWidgetMac::ShouldWindowContentsBeTransparent() const {
-  // On Windows, this returns false when DWM is unavailable (e.g. XP, RDP or
-  // classic mode). OSX always has a compositing window manager.
-  return true;
+  // On Windows, this returns true when Aero is enabled which draws the titlebar
+  // with translucency.
+  return false;
 }
 
 void NativeWidgetMac::FrameTypeChanged() {