Make DesktopWindowTreeHostX11::ShouldWindowContentsBeTransparent() relies on argb visual flag

ui/views/test/widget_test.h

 // Copyright 2013 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.
 
 #ifndef UI_VIEWS_TEST_WIDGET_TEST_H_
 #define UI_VIEWS_TEST_WIDGET_TEST_H_
 
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "ui/gfx/native_widget_types.h"
@@ skipping 71 matching lines @@
 
   // Return the event processor for |widget|. On aura platforms, this is an
   // aura::WindowEventDispatcher. Otherwise, it is a bridge to the OS event
   // processor.
   static ui::EventProcessor* GetEventProcessor(Widget* widget);
 
   // Get the InputMethodDelegate, for setting on a Mock InputMethod in tests.
   static ui::internal::InputMethodDelegate* GetInputMethodDelegateForWidget(
       Widget* widget);
 
+  // Return true if |window| is transparent according to the native platform.
+  static bool IsNativeWindowTransparent(gfx::NativeWindow window);
+
  private:
   DISALLOW_COPY_AND_ASSIGN(WidgetTest);
 };
 
 // A helper WidgetDelegate for tests that require hooks into WidgetDelegate
 // calls, and removes some of the boilerplate for initializing a Widget. Calls
 // Widget::CloseNow() when destroyed if it hasn't already been done.
 class TestDesktopWidgetDelegate : public WidgetDelegate {
  public:
   TestDesktopWidgetDelegate();
@@ skipping 45 matching lines @@
  private:
   View* view_;
 
   DISALLOW_COPY_AND_ASSIGN(TestInitialFocusWidgetDelegate);
 };
 
 }  // namespace test
 }  // namespace views
 
 #endif  // UI_VIEWS_TEST_WIDGET_TEST_H_