[iOS Clean] Created OverlayService.

ios/clean/chrome/browser/ui/overlays/overlay_service_factory.mm

+// 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.
+
+#import "ios/clean/chrome/browser/ui/overlays/overlay_service_factory.h"
+
+#include <memory>
+
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "base/memory/singleton.h"
+#include "components/keyed_service/ios/browser_state_dependency_manager.h"
+#include "ios/chrome/browser/browser_state/chrome_browser_state.h"
+#import "ios/clean/chrome/browser/ui/overlays/overlay_service_impl.h"
+#import "ios/shared/chrome/browser/ui/browser_list/browser_list.h"
+#import "ios/web/public/certificate_policy_cache.h"
+#import "ios/web/public/web_state/session_certificate_policy_cache.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+// static
+OverlayService* OverlayServiceFactory::GetForBrowserState(
+    ios::ChromeBrowserState* browser_state) {
+  return static_cast<OverlayService*>(
+      GetInstance()->GetServiceForBrowserState(browser_state, true));
+}
+
+// static
+OverlayServiceFactory* OverlayServiceFactory::GetInstance() {
+  return base::Singleton<OverlayServiceFactory>::get();
+}
+
+OverlayServiceFactory::OverlayServiceFactory()
+    : BrowserStateKeyedServiceFactory(
+          "OverlayService",
+          BrowserStateDependencyManager::GetInstance()) {}
+
+OverlayServiceFactory::~OverlayServiceFactory() {}
+
+std::unique_ptr<KeyedService> OverlayServiceFactory::BuildServiceInstanceFor(
+    web::BrowserState* context) const {
+  ios::ChromeBrowserState* browser_state =
+      ios::ChromeBrowserState::FromBrowserState(context);
+  // It is safe to use base::Unretained here as OverlayServiceImpl
+  // will be destroyed before the ChromeBrowserState (as it is a KeyedService).
+  return base::MakeUnique<OverlayServiceImpl>(
+      BrowserList::FromBrowserState(browser_state));
+}