Add app.window.alphaEnabled() and onAlphaEnabledChanged.

ui/views/widget/widget.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/widget.h"
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 969 matching lines @@
                              last_mouse_event_position_,
                              last_mouse_event_position_,
                              ui::EF_IS_SYNTHESIZED, 0);
   root_view_->OnMouseMoved(mouse_event);
 }
 
 void Widget::OnRootViewLayout() {
   native_widget_->OnRootViewLayout();
 }
 
+bool Widget::IsTranslucentWindowOpacitySupported() const {
+  return native_widget_->IsTranslucentWindowOpacitySupported();
+}
+
 void Widget::OnOwnerClosing() {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // Widget, NativeWidgetDelegate implementation:
 
 bool Widget::IsModal() const {
   return widget_delegate_->GetModalType() != ui::MODAL_TYPE_NONE;
 }
 
@@ skipping 507 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // internal::NativeWidgetPrivate, NativeWidget implementation:
 
 internal::NativeWidgetPrivate* NativeWidgetPrivate::AsNativeWidgetPrivate() {
   return this;
 }
 
 }  // namespace internal
 }  // namespace views