Crasher workaround

chrome/browser/tab_contents/interstitial_page.cc

 // Copyright (c) 2006-2008 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 "chrome/browser/tab_contents/interstitial_page.h"
 
 #include "base/compiler_specific.h"
 #include "base/message_loop.h"
 #include "base/thread.h"
 #include "chrome/browser/browser_list.h"
@@ skipping 317 matching lines @@
   // this, navigating in a UI test to a URL that triggers an interstitial would
   // hang.
   tab_->SetIsLoading(false, NULL);
 }
 
 void InterstitialPage::UpdateTitle(RenderViewHost* render_view_host,
                                    int32 page_id,
                                    const std::wstring& title) {
   DCHECK(render_view_host == render_view_host_);
   NavigationEntry* entry = tab_->controller().GetActiveEntry();
+  if (!entry) {
+    // Crash reports from the field indicate this can be NULL.
+    // This is unexpected as InterstitialPages constructed with the
+    // new_navigation flag set to true create a transient navigation entry
+    // (that is returned as the active entry). And the only case so far of
+    // interstitial created with that flag set to false is with the
+    // SafeBrowsingBlockingPage, when the resource triggering the interstitial
+    // is a sub-resource, meaning the main page has already been loaded and a
+    // navigation entry should have been created.
+    NOTREACHED();
+    return;
+  }
+
   // If this interstitial is shown on an existing navigation entry, we'll need
   // to remember its title so we can revert to it when hidden.
   if (!new_navigation_ && !should_revert_tab_title_) {
     original_tab_title_ = UTF16ToWideHack(entry->title());
     should_revert_tab_title_ = true;
   }
   entry->set_title(WideToUTF16Hack(title));
   tab_->NotifyNavigationStateChanged(TabContents::INVALIDATE_TAB);
 }
 
@@ skipping 216 matching lines @@
 
 void InterstitialPage::InterstitialPageRVHViewDelegate::HandleMouseLeave() {
   if (interstitial_page_->tab() && interstitial_page_->tab()->GetViewDelegate())
     interstitial_page_->tab()->GetViewDelegate()->HandleMouseLeave();
 }
 
 void InterstitialPage::InterstitialPageRVHViewDelegate::OnFindReply(
     int request_id, int number_of_matches, const gfx::Rect& selection_rect,
     int active_match_ordinal, bool final_update) {
 }