[iOS] Add FakeSyncService and factory for testing

ios/public/test/fake_sync_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/public/test/fake_sync_service_factory.h"
+
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/keyed_service/core/keyed_service.h"
+#include "components/keyed_service/ios/browser_state_dependency_manager.h"
+#include "components/sync_driver/fake_sync_service.h"
+
+namespace {
+
+class KeyedFakeSyncService : public KeyedService {
+ public:
+  KeyedFakeSyncService(sync_driver::FakeSyncService* service)
+      : fake_sync_service_(service) {
+    DCHECK(fake_sync_service_);
+  }
+
+  sync_driver::FakeSyncService* fake_sync_service() {
+    return fake_sync_service_.get();
+  }
+
+ private:
+  scoped_ptr<sync_driver::FakeSyncService> fake_sync_service_;
+};
+
+}  // namespace
+
+namespace ios {
+
+// static
+FakeSyncServiceFactory* FakeSyncServiceFactory::GetInstance() {
+  return Singleton<FakeSyncServiceFactory>::get();
+}
+
+// static
+sync_driver::FakeSyncService* FakeSyncServiceFactory::GetForBrowserState(
+    web::BrowserState* browser_state) {
+  return static_cast<KeyedFakeSyncService*>(
+             FakeSyncServiceFactory::GetInstance()->GetServiceForBrowserState(
+                 browser_state, true))->fake_sync_service();
+}
+
+KeyedService* FakeSyncServiceFactory::BuildServiceInstanceFor(
+    web::BrowserState* context) const {
+  return new KeyedFakeSyncService(new sync_driver::FakeSyncService);
+}
+
+FakeSyncServiceFactory::FakeSyncServiceFactory()
+    : BrowserStateKeyedServiceFactory(
+          "FakeSyncService",
+          BrowserStateDependencyManager::GetInstance()) {
+}
+
+FakeSyncServiceFactory::~FakeSyncServiceFactory() {
+}
+
+}  // namespace ios