Additional checks/calls for cases when WebUI may be already gone but OOBE screen instance is not

chrome/browser/chromeos/login/network_screen.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_NETWORK_SCREEN_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_NETWORK_SCREEN_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
 #include "base/string16.h"
@@ skipping 16 matching lines @@
   // WizardScreen implementation:
   virtual void PrepareToShow() OVERRIDE;
   virtual void Show() OVERRIDE;
   virtual void Hide() OVERRIDE;
   virtual std::string GetName() const OVERRIDE;
 
   // NetworkLibrary::NetworkManagerObserver implementation:
   virtual void OnNetworkManagerChanged(NetworkLibrary* network_lib) OVERRIDE;
 
   // NetworkScreenActor::Delegate implementation:
+  virtual void OnActorDestroyed(NetworkScreenActor* actor) OVERRIDE;
   virtual void OnContinuePressed() OVERRIDE;
 
   NetworkScreenActor* actor() const { return actor_; }
 
  protected:
   // Subscribes NetworkScreen to the network change notification,
   // forces refresh of current network state.
   virtual void Refresh();
 
  private:
@@ skipping 34 matching lines @@
   base::OneShotTimer<NetworkScreen> connection_timer_;
 
   NetworkScreenActor* actor_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkScreen);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_NETWORK_SCREEN_H_