If replacing a safebrowsing interstitial, don't call DontProceed on the old one.

chrome/browser/safe_browsing/safe_browsing_blocking_page.cc

 // 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.
 //
 // Implementation of the SafeBrowsingBlockingPage class.
 
 #include "chrome/browser/safe_browsing/safe_browsing_blocking_page.h"
 
 #include <string>
 
@@ skipping 440 matching lines @@
                                           main_frame_url, resources);
 }
 
 // static
 void SafeBrowsingBlockingPage::ShowBlockingPage(
     SafeBrowsingUIManager* ui_manager,
     const UnsafeResource& unsafe_resource) {
   DVLOG(1) << __func__ << " " << unsafe_resource.url.spec();
   WebContents* web_contents = unsafe_resource.web_contents_getter.Run();
 
-  InterstitialPage* interstitial =
-      InterstitialPage::GetInterstitialPage(web_contents);
-  if (interstitial && !unsafe_resource.is_subresource) {
-    // There is already an interstitial showing and we are about to display a
-    // new one for the main frame. Just hide the current one, it is now
-    // irrelevent
-    interstitial->DontProceed();
-    interstitial = NULL;
-  }
-
-  if (!interstitial) {
-    // There are no interstitial currently showing in that tab, go ahead and
-    // show this interstitial.
+  if (!InterstitialPage::GetInterstitialPage(web_contents) ||
+      !unsafe_resource.is_subresource) {
+    // There is no interstitial currently showing in that tab, or we are about
+    // to display a new one for the main frame. If there is already an
+    // interstitial, showing the new one will automatically hide the old one.
     content::NavigationEntry* entry =
         unsafe_resource.GetNavigationEntryForResource();
     SafeBrowsingBlockingPage* blocking_page =
         CreateBlockingPage(ui_manager, web_contents,
                            entry ? entry->GetURL() : GURL(), unsafe_resource);
     blocking_page->Show();
     return;
   }
 
   // This is an interstitial for a page's resource, let's queue it.
@@ skipping 283 matching lines @@
       l10n_util::GetStringFUTF16(IDS_PHISHING_V4_EXPLANATION_PARAGRAPH,
                                  GetFormattedHostName()));
   load_time_data->SetString(
       "finalParagraph",
       l10n_util::GetStringUTF16(IDS_PHISHING_V4_PROCEED_AND_REPORT_PARAGRAPH));
 
   PopulateExtendedReportingOption(load_time_data);
 }
 
 }  // namespace safe_browsing