NoState Prefetch: nostate prefetch browser tests.

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"
@@ skipping 12 matching lines @@
 // 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* GetForBrowserContext(
       content::BrowserContext* context);
 
   static PrerenderManagerFactory* GetInstance();
 
+  // Sets a global TestingFactoryFunction that will be used to create
+  // PrerenderManagers for all BrowserContexts.
+  //
+  // In-process browser tests cannot use KeyedServiceFactory::SetTestingFactory
+  // to override the PrerenderManagerFactory. The test instance is started
+  // before there is a browser or profile and so it is not possible to
+  // SetTestingFactory. By the time the first testing hook after browser
+  // creation is called (content::BrowserTestBase::SetUpOnMainThread), the
+  // PrerenderManager instance has already by created (eg, by the prerender tab

[pasko, 2016/09/30 18:29:20]

nit: s/by/been/

(but actually it is better to remove this hack entirely, see other comment)

+  // helper), and it is too late. This testing_create_function overrides
+  // PrerenderManager creation for all profiles.
+  static void set_testing_create_function(
+      TestingFactoryFunction create_function) {
+    testing_create_function_ = create_function;
+  }
+
  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;
+
+  static TestingFactoryFunction testing_create_function_;
 };
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_MANAGER_FACTORY_H_