Ensure that PageID's of prerendered pages do not exceed the Page ID of the

chrome/browser/prerender/prerender_contents.h

 // Copyright (c) 2011 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_PRERENDER_PRERENDER_CONTENTS_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_CONTENTS_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 236 matching lines @@
   // is to be used (true).
   // TODO(cbentzel): Remove once new approach looks stable.
   static bool UseTabContents() {
     return true;
   }
 
   // Applies all the URL history encountered during prerendering to the
   // new tab.
   void CommitHistory(TabContents* tc);
 
+  int32 starting_page_id() { return starting_page_id_; }
+
  protected:
   PrerenderContents(PrerenderManager* prerender_manager,
                     Profile* profile,
                     const GURL& url,
                     const GURL& referrer);
 
   const GURL& prerender_url() const { return prerender_url_; }
 
   NotificationRegistrar& notification_registrar() {
     return notification_registrar_;
@@ skipping 83 matching lines @@
   scoped_ptr<TabContentsWrapper> prerender_contents_;
 
   scoped_ptr<PrerenderRenderViewHostObserver> render_view_host_observer_;
 
   scoped_ptr<TabContentsDelegateImpl> tab_contents_delegate_;
 
   // These are -1 before a RenderView is created.
   int child_id_;
   int route_id_;
 
+  // Page ID at which prerendering started.
+  int32 starting_page_id_;
+
+  // Offset by which to offset prerendered pages
+  static const int32 kPrerenderPageIdOffset = 10;
+
   DISALLOW_COPY_AND_ASSIGN(PrerenderContents);
 };
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_CONTENTS_H_