Introduce Identity Service and its initial usage

services/identity/identity_service.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 "services/identity/identity_service.h"
+
+#include "services/identity/identity_manager.h"
+#include "services/service_manager/public/cpp/connection.h"
+#include "services/service_manager/public/cpp/interface_registry.h"
+#include "services/service_manager/public/cpp/service_context.h"
+
+namespace identity {
+
+IdentityService::IdentityService(SigninManagerBase* signin_manager)
+    : signin_manager_(signin_manager) {}
+
+IdentityService::~IdentityService() {}
+
+void IdentityService::OnStart() {}
+
+bool IdentityService::OnConnect(const service_manager::ServiceInfo& remote_info,
+                                service_manager::InterfaceRegistry* registry) {
+  registry->AddInterface<mojom::IdentityManager>(this);
+  return true;
+}
+
+void IdentityService::Create(const service_manager::Identity& remote_identity,
+                             mojom::IdentityManagerRequest request) {
+  IdentityManager::Create(std::move(request), signin_manager_);
+}
+
+}  // namespace identity