Remove ServiceIsNullForTesting override for FaviconServiceFactory

ios/chrome/browser/favicon/favicon_service_factory.h

Index: ios/chrome/browser/favicon/favicon_service_factory.h
diff --git a/ios/chrome/browser/favicon/favicon_service_factory.h b/ios/chrome/browser/favicon/favicon_service_factory.h
index 53c339e442312134a8def9982744ff415b748596..1e43ce5818da244fbbdaa57ff01bfa411d9fbb9a 100644
--- a/ios/chrome/browser/favicon/favicon_service_factory.h
+++ b/ios/chrome/browser/favicon/favicon_service_factory.h
@@ -32,6 +32,10 @@ class FaviconServiceFactory : public BrowserStateKeyedServiceFactory {
       ios::ChromeBrowserState* browser_state,
       ServiceAccessType access_type);
   static FaviconServiceFactory* GetInstance();
+  // Returns the default factory used to build IOSChromeLargeIconService. Can be

[sdefresne, 2015/11/21 01:52:03]

nit: blank line before the comment (as you did in
ios/chrome/browser/favicon/ios_chrome_large_icon_service_factory.h).

s/IOSChromeLargeIconService/FaviconServiceFactory/ (and below)
  ^ a.k.a. copy-n-paste fail ;-)

+  // registered with SetTestingFactory to use the IOSChromeLargeIconService
+  // instance during testing.
+  static TestingFactoryFunction GetDefaultFactory();
 
  private:
   friend struct base::DefaultSingletonTraits<FaviconServiceFactory>;