Set null testing Favicon factories on iOS too

ios/chrome/browser/favicon/ios_chrome_large_icon_service_factory.cc

 // Copyright 2015 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.
 
 #include "ios/chrome/browser/favicon/ios_chrome_large_icon_service_factory.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/singleton.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 14 matching lines @@
 
 // static
 IOSChromeLargeIconServiceFactory*
 IOSChromeLargeIconServiceFactory::GetInstance() {
   return base::Singleton<IOSChromeLargeIconServiceFactory>::get();
 }
 
 IOSChromeLargeIconServiceFactory::IOSChromeLargeIconServiceFactory()
     : BrowserStateKeyedServiceFactory(
           "LargeIconService",
-          BrowserStateDependencyManager::GetInstance()) {}
+          BrowserStateDependencyManager::GetInstance()) {
+  DependsOn(ios::FaviconServiceFactory::GetInstance());
+}
 
 IOSChromeLargeIconServiceFactory::~IOSChromeLargeIconServiceFactory() {}
 
 std::unique_ptr<KeyedService>
 IOSChromeLargeIconServiceFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   ios::ChromeBrowserState* browser_state =
       ios::ChromeBrowserState::FromBrowserState(context);
 
   return base::MakeUnique<favicon::LargeIconService>(
       ios::FaviconServiceFactory::GetForBrowserState(
           browser_state, ServiceAccessType::EXPLICIT_ACCESS),
       web::WebThread::GetBlockingPool());
 }
 
 web::BrowserState* IOSChromeLargeIconServiceFactory::GetBrowserStateToUse(
     web::BrowserState* context) const {
   return GetBrowserStateOwnInstanceInIncognito(context);
 }
+
+bool IOSChromeLargeIconServiceFactory::ServiceIsNULLWhileTesting() const {
+  return true;
+}