[NoStatePrefetch] Add performance histograms.

chrome/browser/prerender/prerender_manager_factory.h

 // Copyright (c) 2012 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_FACTORY_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_FACTORY_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
+namespace content {
+class BrowserContext;
+}
+
 class Profile;
 
 namespace prerender {
 
 class PrerenderManager;
 
 // Singleton that owns all PrerenderManagers and associates them with Profiles.
 // Listens for the Profile's destruction notification and cleans up the
 // associated PrerenderManager.
 class PrerenderManagerFactory : public BrowserContextKeyedServiceFactory {
  public:
   // Returns the PrerenderManager for |profile|.
-  static PrerenderManager* GetForProfile(Profile* profile);
+  static PrerenderManager* GetForBrowserContext(

[mattcary, 2016/09/14 12:33:21]

Why change this? Is it just cleanup or is there a functional reason?

[droger, 2016/09/14 14:15:42]

It's mainly a cleanup. I can do this a separate CL if this is better, or even
work around it.

I did this because I added a new call to this function in a place where I have a
BrowserContext and not a Profile.

I could convert the BrowserContext to Profile instead (like many other callers
do), but it turns out that the function does not actually need a Profile and a
BrowserContext is enough. So I figured the cleaner way is to fix the function
and all the callers to use BrowserContext.

[mattcary, 2016/09/14 14:19:39]

Ok, thanks for the context.

No need to put that in a separate CL from my perspective.

+      content::BrowserContext* context);
 
   static PrerenderManagerFactory* GetInstance();
 
  private:
   friend struct base::DefaultSingletonTraits<PrerenderManagerFactory>;
 
   PrerenderManagerFactory();
   ~PrerenderManagerFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
 };
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_FACTORY_H_