[NoStatePrefetch] Add performance histograms.

chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc

Index: chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
diff --git a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
index 233be0c800fbd1d77589e410a4a7c29a016c9026..f2235ac00eaa183f2124516e219814e0d2d9f114 100644
--- a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
+++ b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
@@ -154,11 +154,8 @@ prerender::PrerenderManager* GetPrerenderManager(
   if (!browser_context)
     return NULL;
 
-  Profile* profile = Profile::FromBrowserContext(browser_context);
-  if (!profile)
-    return NULL;
-
-  return prerender::PrerenderManagerFactory::GetForProfile(profile);
+  return prerender::PrerenderManagerFactory::GetForBrowserContext(
+      browser_context);
 }
 
 void UpdatePrerenderNetworkBytesCallback(content::WebContents* web_contents,