Make PrerenderHandle an observer of PrerenderContents.

chrome/renderer/prerender/prerender_dispatcher.h

Index: chrome/renderer/prerender/prerender_dispatcher.h
diff --git a/chrome/renderer/prerender/prerender_dispatcher.h b/chrome/renderer/prerender/prerender_dispatcher.h
index c72620dda11c76cf79025596373b6c7f0080d1b7..1c9811699e8df54b6f88717af11365a22cc45ebb 100644
--- a/chrome/renderer/prerender/prerender_dispatcher.h
+++ b/chrome/renderer/prerender/prerender_dispatcher.h
@@ -31,8 +31,10 @@ class PrerenderDispatcher : public content::RenderProcessObserver,
  private:
   friend class PrerenderDispatcherTest;
 
-  void OnAddPrerenderURL(const GURL& url);
-  void OnRemovePrerenderURL(const GURL& url);
+  // Message handlers for messages from the browser process.
+  void OnPrerenderStart(int prerender_id);
+  void OnPrerenderAddAlias(int prerender_id, const GURL& url);
+  void OnPrerenderStop(int prerender_id);
 
   // From RenderProcessObserver:
   virtual bool OnControlMessageReceived(const IPC::Message& message) OVERRIDE;
@@ -42,8 +44,14 @@ class PrerenderDispatcher : public content::RenderProcessObserver,
   virtual void cancel(const WebKit::WebPrerender& prerender) OVERRIDE;
   virtual void abandon(const WebKit::WebPrerender& prerender) OVERRIDE;
 
-  typedef std::map<GURL, int> PrerenderMap;
-  PrerenderMap prerender_urls_;
+  // From WebKit, prerender elements launched by renderers in our process.
+  // TODO(gavinp): Store a WebKit::WebPrerender* here once the WebKit API
+  // updates to allow this.
+  std::map<int, GURL> prerenders_;
+
+  // From the browser process, which prerenders are running, indexed by URL.
+  // Updated by the browser processes as aliases are discovered.
+  std::multimap<GURL, int> running_prerender_urls_;
 };
 
 }  // namespace prerender