Add Desktop iOS promotion logging to chrome ios app.

ios/chrome/browser/desktop_promotion/desktop_promotion_sync_service_factory.cc

+// Copyright 2017 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/desktop_promotion/desktop_promotion_sync_service_factory.h"
+
+#include "base/memory/ptr_util.h"
+
+#include "components/keyed_service/ios/browser_state_dependency_manager.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state.h"
+#include "ios/chrome/browser/desktop_promotion/desktop_promotion_sync_service.h"
+#include "ios/chrome/browser/sync/ios_chrome_profile_sync_service_factory.h"
+
+// static
+DesktopPromotionSyncService*
+DesktopPromotionSyncServiceFactory::GetForBrowserState(
+    ios::ChromeBrowserState* browser_state) {
+  return static_cast<DesktopPromotionSyncService*>(
+      GetInstance()->GetServiceForBrowserState(browser_state, true));
+}
+
+// static
+DesktopPromotionSyncServiceFactory*
+DesktopPromotionSyncServiceFactory::GetInstance() {
+  return base::Singleton<DesktopPromotionSyncServiceFactory>::get();
+}
+
+DesktopPromotionSyncServiceFactory::DesktopPromotionSyncServiceFactory()
+    : BrowserStateKeyedServiceFactory(
+          "DesktopPromotionSyncService",
+          BrowserStateDependencyManager::GetInstance()) {
+  DependsOn(IOSChromeProfileSyncServiceFactory::GetInstance());
+}
+
+DesktopPromotionSyncServiceFactory::~DesktopPromotionSyncServiceFactory() =
+    default;
+
+std::unique_ptr<KeyedService>
+DesktopPromotionSyncServiceFactory::BuildServiceInstanceFor(
+    web::BrowserState* context) const {
+  ios::ChromeBrowserState* browser_state =
+      ios::ChromeBrowserState::FromBrowserState(context);
+  return base::MakeUnique<DesktopPromotionSyncService>(
+      browser_state->GetPrefs(),
+      IOSChromeProfileSyncServiceFactory::GetForBrowserState(browser_state));
+}
+
+bool DesktopPromotionSyncServiceFactory::ServiceIsNULLWhileTesting() const {
+  return true;
+}