[Offline Pages] Add a GCMAppHandler for offline page prefetch.

chrome/browser/offline_pages/prefetch/prefetch_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 "chrome/browser/offline_pages/prefetch/prefetch_service_factory.h"
+
+#include "base/memory/ptr_util.h"
+#include "base/memory/singleton.h"
+#include "chrome/browser/gcm/gcm_profile_service_factory.h"
+#include "components/gcm_driver/gcm_driver.h"
+#include "components/gcm_driver/gcm_profile_service.h"
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "components/offline_pages/core/prefetch/prefetch_gcm_app_handler.h"
+#include "components/offline_pages/core/prefetch/prefetch_service_impl.h"
+#include "content/public/browser/browser_context.h"
+
+namespace offline_pages {
+
+PrefetchServiceFactory::PrefetchServiceFactory()
+    : BrowserContextKeyedServiceFactory(
+          "OfflinePagePrefetchService",
+          BrowserContextDependencyManager::GetInstance()) {
+  DependsOn(gcm::GCMProfileServiceFactory::GetInstance());
+}
+
+// static
+PrefetchServiceFactory* PrefetchServiceFactory::GetInstance() {
+  return base::Singleton<PrefetchServiceFactory>::get();
+}
+
+// static
+PrefetchService* PrefetchServiceFactory::GetForBrowserContext(
+    content::BrowserContext* context) {
+  return static_cast<PrefetchService*>(
+      GetInstance()->GetServiceForBrowserContext(context, true));
+}
+
+KeyedService* PrefetchServiceFactory::BuildServiceInstanceFor(
+    content::BrowserContext* context) const {
+  PrefetchGCMAppHandler* app_handler = new PrefetchGCMAppHandler();
+  auto service =
+      base::MakeUnique<PrefetchServiceImpl>(base::WrapUnique(app_handler));
+
+  gcm::GCMProfileServiceFactory::GetForProfile(context)
+      ->driver()
+      ->AddAppHandler(app_handler->app_id(), app_handler);
+  return service.release();
+}
+
+bool PrefetchServiceFactory::ServiceIsCreatedWithBrowserContext() const {
+  // PrefetchService is designed to be very lightweight to create, this way it
+  // can manage the lifetime of long-lived objects such as the GCMAppHandler and
+  // the daily-usage stats collector without burdening Chrome too much at
+  // startup time.
+  return true;
+}
+
+}  // namespace offline_pages