NTP: don't allow navigateContentWindow to navigate where it pleases.

chrome/browser/search/instant_service.h

 // 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.
 
 #ifndef CHROME_BROWSER_SEARCH_INSTANT_SERVICE_H_
 #define CHROME_BROWSER_SEARCH_INSTANT_SERVICE_H_
 
 #include <set>
 #include <vector>
 
@@ skipping 69 matching lines @@
   // necessary. Investigate more and remove this from here.
   void UpdateThemeInfo();
 
   // Invoked by the InstantController to update most visited items details for
   // NTP.
   void UpdateMostVisitedItemsInfo();
 
   // Sends the current set of search URLs to a renderer process.
   void SendSearchURLsToRenderer(content::RenderProcessHost* rph);
 
+  // Used to validate that the URL the NTP is trying to navigate to is actually
+  // a URL on the most visited items / suggested items list.
+  bool IsValidURLForNavigation(const GURL& url) const;
+
   InstantSearchPrerenderer* instant_search_prerenderer() {
     return instant_prerenderer_.get();
   }
 
  private:
   friend class InstantExtendedTest;
   friend class InstantServiceTest;
   friend class InstantTestBase;
   friend class InstantUnitTestBase;
 
@@ skipping 80 matching lines @@
   // Suggestions Service to fetch server suggestions.
   suggestions::SuggestionsService* suggestions_service_;
 
   // Used for Top Sites async retrieval.
   base::WeakPtrFactory<InstantService> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InstantService);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_INSTANT_SERVICE_H_