Add app.window.alphaEnabled() and onAlphaEnabledChanged.

ui/views/widget/widget_unittest.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 <algorithm>
 #include <set>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 606 matching lines @@
     widget->IsMouseEventsEnabled();
     widget->SetNativeWindowProperty("xx", widget);
     widget->GetNativeWindowProperty("xx");
     widget->GetFocusTraversable();
     widget->GetLayer();
     widget->ReorderNativeViews();
     widget->SetCapture(widget->GetRootView());
     widget->ReleaseCapture();
     widget->HasCapture();
     widget->GetWorkAreaBoundsInScreen();
+    widget->IsTranslucentWindowOpacitySupported();
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WidgetWithDestroyedNativeViewTest);
 };
 
 TEST_F(WidgetWithDestroyedNativeViewTest, Test) {
   {
     Widget widget;
     Widget::InitParams params = CreateParams(Widget::InitParams::TYPE_POPUP);
@@ skipping 1745 matching lines @@
   child_widget.Init(child_params);
   child_widget.AddObserver(&observer);
   child_widget.Show();
 
   parent_widget.CloseNow();
 }
 #endif  // !defined(OS_CHROMEOS)
 
 }  // namespace test
 }  // namespace views