Add app.window.alphaEnabled() and onAlphaEnabledChanged.

ui/views/widget/native_widget_aura.h

 // 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.
 
 #ifndef UI_VIEWS_WIDGET_NATIVE_WIDGET_AURA_H_
 #define UI_VIEWS_WIDGET_NATIVE_WIDGET_AURA_H_
 
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "ui/aura/client/focus_change_observer.h"
@@ skipping 114 matching lines @@
   virtual void ClearNativeFocus() OVERRIDE;
   virtual gfx::Rect GetWorkAreaBoundsInScreen() const OVERRIDE;
   virtual Widget::MoveLoopResult RunMoveLoop(
       const gfx::Vector2d& drag_offset,
       Widget::MoveLoopSource source,
       Widget::MoveLoopEscapeBehavior escape_behavior) OVERRIDE;
   virtual void EndMoveLoop() OVERRIDE;
   virtual void SetVisibilityChangedAnimationsEnabled(bool value) OVERRIDE;
   virtual ui::NativeTheme* GetNativeTheme() const OVERRIDE;
   virtual void OnRootViewLayout() OVERRIDE;
+  virtual bool IsTranslucentWindowOpacitySupported() const OVERRIDE;
   virtual void RepostNativeEvent(gfx::NativeEvent native_event) OVERRIDE;
 
   // Overridden from views::InputMethodDelegate:
   virtual void DispatchKeyEventPostIME(const ui::KeyEvent& key) OVERRIDE;
 
   // Overridden from aura::WindowDelegate:
   virtual gfx::Size GetMinimumSize() const OVERRIDE;
   virtual gfx::Size GetMaximumSize() const OVERRIDE;
   virtual void OnBoundsChanged(const gfx::Rect& old_bounds,
                                const gfx::Rect& new_bounds) OVERRIDE;
@@ skipping 75 matching lines @@
 
   scoped_ptr<DropHelper> drop_helper_;
   int last_drop_operation_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeWidgetAura);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_NATIVE_WIDGET_AURA_H_