Fix a race between navigation and an interstitial.

content/browser/frame_host/navigation_controller_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.
 
 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved.
  *     (http://www.torchmobile.com/)
  *
@@ skipping 1862 matching lines @@
   // will force the throbber to start, but WebKit will essentially ignore the
   // navigation, and won't send a message to stop the throbber. To prevent this
   // from happening, we drop the navigation here and stop the slow-to-commit
   // page from loading (which would normally happen during the navigation).
   if (pending_entry_index_ != -1 &&
       pending_entry_index_ == last_committed_entry_index_ &&
       pending_entry_->restore_type() == RestoreType::NONE &&
       pending_entry_->GetTransitionType() & ui::PAGE_TRANSITION_FORWARD_BACK) {
     delegate_->Stop();
 
-    // If an interstitial page is showing, we want to close it to get back
-    // to what was showing before.
-    if (delegate_->GetInterstitialPage())
-      delegate_->GetInterstitialPage()->DontProceed();
+    // If an interstitial page is showing, we want to close it to get back to
+    // what was showing before.
+    //
+    // There are two ways to get the interstitial page given a WebContents.
+    // Because WebContents::GetInterstitialPage() returns null between the
+    // interstitial's Show() method being called and the interstitial becoming
+    // visible, while InterstitialPage::GetInterstitialPage() returns the
+    // interstitial during that time, use the latter.
+    InterstitialPage* interstitial =
+        InterstitialPage::GetInterstitialPage(GetWebContents());
+    if (interstitial)
+      interstitial->DontProceed();
 
     DiscardNonCommittedEntries();
     return;
   }
 
   // If an interstitial page is showing, the previous renderer is blocked and
   // cannot make new requests.  Unblock (and disable) it to allow this
   // navigation to succeed.  The interstitial will stay visible until the
   // resulting DidNavigate.
   if (delegate_->GetInterstitialPage()) {
@@ skipping 337 matching lines @@
   DCHECK(pending_entry_index_ == -1 ||
          pending_entry_ == GetEntryAtIndex(pending_entry_index_));
 }
 
 void NavigationControllerImpl::SetGetTimestampCallbackForTest(
     const base::Callback<base::Time()>& get_timestamp_callback) {
   get_timestamp_callback_ = get_timestamp_callback;
 }
 
 }  // namespace content