Replace more ObserverList with base::ObserverList.

ui/views/widget/widget.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_WIDGET_H_
 #define UI_VIEWS_WIDGET_WIDGET_H_
 
 #include <set>
 #include <stack>
 #include <vector>
@@ skipping 858 matching lines @@
   // Creates and initializes a new InputMethod and returns it, otherwise null.
   scoped_ptr<InputMethod> CreateInputMethod();
 
   // Sets a different InputMethod instance to this widget. The instance
   // must not be initialized, the ownership will be assumed by the widget.
   // It's only for testing purpose.
   void ReplaceInputMethod(InputMethod* input_method);
 
   internal::NativeWidgetPrivate* native_widget_;
 
-  ObserverList<WidgetObserver> observers_;
+  base::ObserverList<WidgetObserver> observers_;
 
-  ObserverList<WidgetRemovalsObserver> removals_observers_;
+  base::ObserverList<WidgetRemovalsObserver> removals_observers_;
 
   // Non-owned pointer to the Widget's delegate. If a NULL delegate is supplied
   // to Init() a default WidgetDelegate is created.
   WidgetDelegate* widget_delegate_;
 
   // The root of the View hierarchy attached to this window.
   // WARNING: see warning in tooltip_manager_ for ordering dependencies with
   // this and tooltip_manager_.
   scoped_ptr<internal::RootView> root_view_;
 
@@ skipping 86 matching lines @@
   bool movement_disabled_;
 
   ScopedObserver<ui::NativeTheme, ui::NativeThemeObserver> observer_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(Widget);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_WIDGET_H_