Cleanup: Refactor ManagedModeInterstitial to not "delete this" in the ctor.

chrome/browser/managed_mode/managed_mode_navigation_observer.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.
 
 #include "chrome/browser/managed_mode/managed_mode_navigation_observer.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/string_util.h"
@@ skipping 215 matching lines @@
         content::BrowserThread::IO, FROM_HERE, base::Bind(callback, false));
     return;
   }
 
   ManagedModeNavigationObserver* navigation_observer =
       ManagedModeNavigationObserver::FromWebContents(web_contents);
   if (navigation_observer)
     navigation_observer->OnRequestBlockedInternal(url);
 
   // Show the interstitial.
-  new ManagedModeInterstitial(web_contents, url, callback);
+  ManagedModeInterstitial::Show(web_contents, url, callback);
 }
 
 void ManagedModeNavigationObserver::OnRequestBlockedInternal(const GURL& url) {
   Time timestamp = Time::Now();  // TODO(bauerb): Use SaneTime when available.
   // Create a history entry for the attempt and mark it as such.
   history::HistoryAddPageArgs add_page_args(
         url, timestamp, web_contents(), 0,
         url, history::RedirectList(),
         content::PAGE_TRANSITION_BLOCKED, history::SOURCE_BROWSED,
         false);
 
   // Add the entry to the history database.
   Profile* profile =
       Profile::FromBrowserContext(web_contents()->GetBrowserContext());
   HistoryService* history_service =
      HistoryServiceFactory::GetForProfile(profile, Profile::IMPLICIT_ACCESS);
 
   // |history_service| is null if saving history is disabled.
   if (history_service)
     history_service->AddPage(add_page_args);
 
   scoped_ptr<NavigationEntry> entry(NavigationEntry::Create());
   entry->SetVirtualURL(url);
   entry->SetTimestamp(timestamp);
   blocked_navigations_.push_back(entry.release());
   ManagedUserService* managed_user_service =
       ManagedUserServiceFactory::GetForProfile(profile);
   managed_user_service->DidBlockNavigation(web_contents());
 }