[NoStatePrefetch] Add performance histograms.

chrome/browser/prerender/prerender_manager_factory.h

Index: chrome/browser/prerender/prerender_manager_factory.h
diff --git a/chrome/browser/prerender/prerender_manager_factory.h b/chrome/browser/prerender/prerender_manager_factory.h
index dbc5fb31bb4de5a1b919fabd5cf4df2389b170c6..46e7e67f2db756bb316e4ada0a1de322763340b4 100644
--- a/chrome/browser/prerender/prerender_manager_factory.h
+++ b/chrome/browser/prerender/prerender_manager_factory.h
@@ -9,6 +9,10 @@
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
+namespace content {
+class BrowserContext;
+}
+
 class Profile;
 
 namespace prerender {
@@ -21,7 +25,8 @@ class PrerenderManager;
 class PrerenderManagerFactory : public BrowserContextKeyedServiceFactory {
  public:
   // Returns the PrerenderManager for |profile|.
-  static PrerenderManager* GetForProfile(Profile* profile);
+  static PrerenderManager* GetForBrowserContext(
+      content::BrowserContext* context);
 
   static PrerenderManagerFactory* GetInstance();