mash: wires up shadows for mash

ui/views/widget/desktop_aura/desktop_window_tree_host_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host_win.h"
 
 #include "base/memory/ptr_util.h"
 #include "third_party/skia/include/core/SkPath.h"
 #include "third_party/skia/include/core/SkRegion.h"
 #include "ui/aura/client/aura_constants.h"
@@ skipping 464 matching lines @@
 }
 
 bool DesktopWindowTreeHostWin::ShouldUpdateWindowTransparency() const {
   return true;
 }
 
 bool DesktopWindowTreeHostWin::ShouldUseDesktopNativeCursorManager() const {
   return true;
 }
 
+bool DesktopWindowTreeHostWin::ShouldCreateVisibiltyController() const {
+  return false;

[msw, 2017/02/15 01:37:29]

I guess the wm shadow (and other VisibilityController functionality) is
cros-specific and so this is okay? Were we previously creating visibility
controllers for DesktopNativeWidgetAura on Windows? (perhaps they don't use
TRANSLUCENT_WINDOW?) It'd be nice if VisibilityController had a class comment

[sky, 2017/02/15 03:58:25]

This is wrong, it should be true.

+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // DesktopWindowTreeHostWin, WindowTreeHost implementation:
 
 ui::EventSource* DesktopWindowTreeHostWin::GetEventSource() {
   return this;
 }
 
 gfx::AcceleratedWidget DesktopWindowTreeHostWin::GetAcceleratedWidget() {
   return message_handler_->hwnd();
 }
@@ skipping 497 matching lines @@
 
 // static
 DesktopWindowTreeHost* DesktopWindowTreeHost::Create(
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura) {
   return new DesktopWindowTreeHostWin(native_widget_delegate,
                                       desktop_native_widget_aura);
 }
 
 }  // namespace views