Prerendered tabs use the same SessionStorage namespace as the tab that triggered the prerender.

chrome/browser/prerender/prerender_manager.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_MANAGER_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_
 #pragma once
 
 #include <list>
 #include <string>
@@ skipping 83 matching lines @@
   // set the initial window size of the RenderViewHost used for prerendering.
   // Returns true if the URL was added, false if it was not.
   // If the RenderViewHost source is itself prerendering, the prerender is added
   // as a pending prerender.
   bool AddPrerenderFromLinkRelPrerender(int process_id, int route_id,
                                         const GURL& url, const GURL& referrer);
 
   // Adds a prerender for |url| if valid. As the prerender request is coming
   // from a source without a RenderViewHost (i.e., the omnibox) we don't have a
   // child or route id, or a referrer. This method uses sensible values for
-  // those.
-  bool AddPrerenderFromOmnibox(const GURL& url);
+  // those. The |session_storage_namespace| can be determined at this time,
+  // however, because it is based off of the destination tab rather than the
+  // current contents.

[mmenke, 2011/11/02 02:27:55]

"Destination tab rather than the current contents"?  What does that mean?

[cbentzel, 2011/11/02 15:57:08]

Fixed comment - thanks for pointing this out.

+  bool AddPrerenderFromOmnibox(
+    const GURL& url,
+    SessionStorageNamespace* session_storage_namespace);
 
   // Destroy all prerenders for the given child route id pair and assign a final
   // status to them.
   virtual void DestroyPrerenderForRenderView(int process_id, int view_id,
                                              FinalStatus final_status);
 
   // Cancels all active prerenders.
   void CancelAllPrerenders();
 
   // For a given TabContents that wants to navigate to the URL supplied,
@@ skipping 122 matching lines @@
 
   struct PrerenderContentsData;
   struct NavigationRecord;
 
   class OnCloseTabContentsDeleter;
 
   class MostVisitedSites;
 
   // Adds a prerender for |url| from referrer |referrer| initiated from the
   // RenderViewHost specified by |child_route_id_pair|. The |origin| specifies
-  // how the prerender was added.
+  // how the prerender was added. If the |session_storage_namespace| is NULL,
+  // it is discovered using the RenderViewHost specified by
+  // |child_route_id_pair|.
   bool AddPrerender(
       Origin origin,
       const std::pair<int, int>& child_route_id_pair,
       const GURL& url,
-      const GURL& referrer);
+      const GURL& referrer,
+      SessionStorageNamespace* session_storage_namespace);
 
   // Adds a pending preload issued by the prerendering RenderView identified by
   // |child_route_id_pair|.  If and when that prerendering RenderView is used,
   // the specified prerender will start.
   void AddPendingPrerender(Origin origin,
                            const std::pair<int, int>& child_route_id_pair,
                            const GURL& url,
                            const GURL& referrer);
 
   // Retrieves the PrerenderContents object for the specified URL, if it
@@ skipping 22 matching lines @@
 
   // Posts a task to call PeriodicCleanup.  Results in quicker destruction of
   // objects.  If |this| is deleted before the task is run, the task will
   // automatically be cancelled.
   void PostCleanupTask();
 
   bool IsPrerenderElementFresh(const base::Time start) const;
   void DeleteOldEntries();
   virtual base::Time GetCurrentTime() const;
   virtual base::TimeTicks GetCurrentTimeTicks() const;
-  virtual PrerenderContents* CreatePrerenderContents(const GURL& url,
-                                                     const GURL& referrer,
-                                                     Origin origin,
-                                                     uint8 experiment_id);
+  virtual PrerenderContents* CreatePrerenderContents(
+      SessionStorageNamespace* session_storage_namespace,
+      const GURL& url,
+      const GURL& referrer,
+      Origin origin,
+      uint8 experiment_id);
 
   // Checks if the PrerenderContents has been added to the pending delete list.
   bool IsPendingDelete(PrerenderContents* entry) const;
 
   // Deletes any PrerenderContents that have been added to the pending delete
   // list.
   void DeletePendingDeleteEntries();
 
   // Finds the specified PrerenderContents and returns it, if it exists.
   // Returns NULL otherwise.  Unlike GetEntry, the PrerenderManager maintains
@@ skipping 104 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(PrerenderManager);
 };
 
 PrerenderManager* FindPrerenderManagerUsingRenderProcessId(
     int render_process_id);
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_H_