Disable delegation to picker controller once it is deleted.

chrome/browser/ui/cocoa/intents/web_intent_picker_cocoa2.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_UI_COCOA_INTENTS_WEB_INTENT_PICKER_COCOA2_H_
 #define CHROME_BROWSER_UI_COCOA_INTENTS_WEB_INTENT_PICKER_COCOA2_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/memory/scoped_nsobject.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_mac2.h"
 #include "chrome/browser/ui/intents/web_intent_picker.h"
 #include "chrome/browser/ui/intents/web_intent_picker_model_observer.h"
 
 @class WebIntentPickerViewController;
 
 // An implementation of WebIntentPicker for Cocoa. Bridges between the C++ and
 // the Cocoa WebIntentPickerViewController object.  Note, this will eventually
 // replace WebIntentPickerCocoa, see http://crbug.com/152010.
 class WebIntentPickerCocoa2 : public WebIntentPicker,
                               public WebIntentPickerModelObserver,
                               public ConstrainedWindowMacDelegate2 {
  public:
   WebIntentPickerCocoa2(content::WebContents* web_contents,
                         WebIntentPickerDelegate* delegate,
                         WebIntentPickerModel* model);
   virtual ~WebIntentPickerCocoa2();
 
-  WebIntentPickerDelegate* delegate() const { return delegate_; }
+  WebIntentPickerDelegate* delegate() const {
+    DCHECK(delegate_);
+    return delegate_;
+  }
+
   WebIntentPickerModel* model() const { return model_; }
   content::WebContents* web_contents() const { return web_contents_; }
   ConstrainedWindowMac2* constrained_window() const {
     return constrained_window_.get();
   }
   WebIntentPickerViewController* view_controller() const {
     return view_controller_;
   }
 
   // WebIntentPicker implementation.
   virtual void Close() OVERRIDE;
   virtual void SetActionString(const string16& action) OVERRIDE;
   virtual void OnExtensionInstallSuccess(const std::string& id) OVERRIDE;
   virtual void OnExtensionInstallFailure(const std::string& id) OVERRIDE;
   virtual void OnShowExtensionInstallDialog(
       gfx::NativeWindow parent,
       content::PageNavigator* navigator,
       ExtensionInstallPrompt::Delegate* delegate,
       const ExtensionInstallPrompt::Prompt& prompt) OVERRIDE;
   virtual void OnInlineDispositionAutoResize(const gfx::Size& size) OVERRIDE;
   virtual void OnInlineDispositionHandleKeyboardEvent(
       const content::NativeWebKeyboardEvent& event) OVERRIDE;
   virtual void OnPendingAsyncCompleted() OVERRIDE;
+  virtual void InvalidateDelegate() OVERRIDE;
   virtual void OnInlineDispositionWebContentsLoaded(
       content::WebContents* web_contents) OVERRIDE;
   virtual gfx::Size GetMinInlineDispositionSize() OVERRIDE;
 
   // WebIntentPickerModelObserver implementation.
   virtual void OnModelChanged(WebIntentPickerModel* model) OVERRIDE;
   virtual void OnFaviconChanged(WebIntentPickerModel* model,
                                 size_t index) OVERRIDE;
   virtual void OnExtensionIconChanged(WebIntentPickerModel* model,
                                       const std::string& extension_id) OVERRIDE;
   virtual void OnInlineDisposition(const string16& title,
                                    const GURL& url) OVERRIDE;
 
   // ConstrainedWindowMacDelegate2 implementation.
   virtual void OnConstrainedWindowClosed(
       ConstrainedWindowMac2* window) OVERRIDE;
 
  private:
   content::WebContents* const web_contents_;
-  WebIntentPickerDelegate* const delegate_;
+  WebIntentPickerDelegate* delegate_;
   WebIntentPickerModel* model_;
   scoped_nsobject<WebIntentPickerViewController> view_controller_;
   scoped_ptr<ConstrainedWindowMac2> constrained_window_;
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_INTENTS_WEB_INTENT_PICKER_COCOA2_H_