[iOS] Add FakeSyncService and factory for testing

ios/public/test/test_keyed_service_provider.h

+// 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.
+
+#ifndef IOS_PUBLIC_TEST_TEST_KEYED_SERVICE_PROVIDER_H_
+#define IOS_PUBLIC_TEST_TEST_KEYED_SERVICE_PROVIDER_H_
+
+#include "base/macros.h"
+#include "ios/public/provider/chrome/browser/keyed_service_provider.h"
+
+namespace ios {
+
+class TestKeyedServiceProvider : public KeyedServiceProvider {
+ public:
+  TestKeyedServiceProvider();
+  ~TestKeyedServiceProvider() override;
+
+  // KeyedServiceProvider implementation:
+  KeyedServiceBaseFactory* GetSyncServiceFactory() override;
+  sync_driver::SyncService* GetSyncServiceForBrowserState(
+      ChromeBrowserState* browser_state) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TestKeyedServiceProvider);
+};
+
+}  // namespace ios
+
+#endif  // IOS_PUBLIC_TEST_TEST_KEYED_SERVICE_PROVIDER_H_