Don't crash when closing interstitial pages.

content/browser/frame_host/interstitial_page_impl.h

 // Copyright 2013 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 CONTENT_BROWSER_FRAME_HOST_INTERSTITIAL_PAGE_IMPL_H_
 #define CONTENT_BROWSER_FRAME_HOST_INTERSTITIAL_PAGE_IMPL_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 51 matching lines @@
   virtual void Show() OVERRIDE;
   virtual void Hide() OVERRIDE;
   virtual void DontProceed() OVERRIDE;
   virtual void Proceed() OVERRIDE;
   virtual RenderViewHost* GetRenderViewHostForTesting() const OVERRIDE;
   virtual InterstitialPageDelegate* GetDelegateForTesting() OVERRIDE;
   virtual void DontCreateViewForTesting() OVERRIDE;
   virtual void SetSize(const gfx::Size& size) OVERRIDE;
   virtual void Focus() OVERRIDE;
 
+  // This is called by a hosting WebContents to notify this interstitial page
+  // that it is going away.
+  void WebContentsWillBeDestroyed();
+
   // Allows the user to navigate away by disabling the interstitial, canceling
   // the pending request, and unblocking the hidden renderer.  The interstitial
   // will stay visible until the navigation completes.
   void CancelForNavigation();
 
   // Focus the first (last if reverse is true) element in the interstitial page.
   // Called when tab traversing.
   void FocusThroughTabTraversal(bool reverse);
 
   RenderWidgetHostView* GetView();
@@ skipping 201 matching lines @@
   base::WeakPtrFactory<InterstitialPageImpl> weak_ptr_factory_;
 
   scoped_refptr<SessionStorageNamespace> session_storage_namespace_;
 
   DISALLOW_COPY_AND_ASSIGN(InterstitialPageImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_INTERSTITIAL_PAGE_IMPL_H_