views: Extract Widget observer into its own header file.

chrome/browser/chromeos/login/captive_portal_window_proxy.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 CHROME_BROWSER_CHROMEOS_LOGIN_CAPTIVE_PORTAL_WINDOW_PROXY_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_CAPTIVE_PORTAL_WINDOW_PROXY_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/gfx/native_widget_types.h"
-#include "ui/views/widget/widget.h"
+#include "ui/views/widget/widget_observer.h"
 
 namespace views {
 class Widget;
 }
 
 namespace chromeos {
 
 class CaptivePortalView;
 
 // Delegate interface for CaptivePortalWindowProxy.
 class CaptivePortalWindowProxyDelegate {
  public:
   // Called when a captive portal is detected.
   virtual void OnPortalDetected() = 0;
 
  protected:
   virtual ~CaptivePortalWindowProxyDelegate() {}
 };
 
 // Proxy which manages showing of the window for CaptivePortal sign-in.
-class CaptivePortalWindowProxy : public views::Widget::Observer {
+class CaptivePortalWindowProxy : public views::WidgetObserver {
  public:
   typedef CaptivePortalWindowProxyDelegate Delegate;
 
   CaptivePortalWindowProxy(Delegate* delegate, gfx::NativeWindow parent);
   virtual ~CaptivePortalWindowProxy();
 
   // Shows captive portal window only after a redirection has happened. So it is
   // safe to call this method, when the caller isn't 100% sure that the network
   // is in the captive portal state.
   // Subsequent call to this method would reuses existing view
   // but reloads test page (generate_204).
   void ShowIfRedirected();
 
   // Forces captive portal window show.
   void Show();
 
   // Closes the window.
   void Close();
 
   // Called by CaptivePortalView when URL loading was redirected from the
   // original URL.
   void OnRedirected();
 
   // Called by CaptivePortalView when origin URL is loaded without any
   // redirections.
   void OnOriginalURLLoaded();
 
-  // views::Widget::Observer implementation:
+  // Overridden from views::WidgetObserver:
   virtual void OnWidgetClosing(views::Widget* widget) OVERRIDE;
 
  private:
   Delegate* delegate_;
   views::Widget* widget_;
   scoped_ptr<CaptivePortalView> captive_portal_view_;
   gfx::NativeWindow parent_;
 
   DISALLOW_COPY_AND_ASSIGN(CaptivePortalWindowProxy);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_CAPTIVE_PORTAL_WINDOW_PROXY_H_