Don't crash when closing interstitial pages.

content/browser/frame_host/interstitial_page_impl.cc

 // 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.
 
 #include "content/browser/frame_host/interstitial_page_impl.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 339 matching lines @@
     default:
       NOTREACHED();
   }
 }
 
 void InterstitialPageImpl::NavigationEntryCommitted(
     const LoadCommittedDetails& load_details) {
   OnNavigatingAwayOrTabClosing();
 }
 
+void InterstitialPageImpl::WebContentsWillBeDestroyed() {
+  OnNavigatingAwayOrTabClosing();
+}
+
 void InterstitialPageImpl::WebContentsDestroyed(WebContents* web_contents) {
+  // WebContentsImpl will only call WebContentsWillBeDestroyed for interstitial
+  // pages that it knows about, pages that called
+  // WebContentsImpl::AttachInterstitialPage. But it's possible to have an
+  // interstitial page that never progressed that far. In that case, ensure that
+  // this interstitial page is destroyed. (And if it was attached, and
+  // OnNavigatingAwayOrTabClosing was called, it's safe to call
+  // OnNavigatingAwayOrTabClosing twice.)
   OnNavigatingAwayOrTabClosing();
 }
 
 bool InterstitialPageImpl::OnMessageReceived(RenderFrameHost* render_frame_host,
                                              const IPC::Message& message) {
   return OnMessageReceived(message);
 }
 
 bool InterstitialPageImpl::OnMessageReceived(RenderViewHost* render_view_host,
                                              const IPC::Message& message) {
@@ skipping 527 matching lines @@
 
   web_contents->GetDelegateView()->TakeFocus(reverse);
 }
 
 void InterstitialPageImpl::InterstitialPageRVHDelegateView::OnFindReply(
     int request_id, int number_of_matches, const gfx::Rect& selection_rect,
     int active_match_ordinal, bool final_update) {
 }
 
 }  // namespace content