[Media Router] Factor extension-related logic out of MediaRouterMojoImpl

chrome/browser/media/router/event_page_request_manager_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/media/router/event_page_request_manager_factory.h"
+
+#include "chrome/browser/media/router/event_page_request_manager.h"
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "extensions/browser/process_manager_factory.h"
+
+using content::BrowserContext;
+
+namespace media_router {
+
+// static
+EventPageRequestManager*
+EventPageRequestManagerFactory::GetApiForBrowserContext(
+    BrowserContext* context) {
+  DCHECK(context);
+  // GetServiceForBrowserContext returns a KeyedService hence the static_cast<>
+  // to return a pointer to EventPageRequestManager.
+  return static_cast<EventPageRequestManager*>(
+      GetInstance()->GetServiceForBrowserContext(context, true));
+}
+
+// static
+EventPageRequestManagerFactory* EventPageRequestManagerFactory::GetInstance() {
+  return base::Singleton<EventPageRequestManagerFactory>::get();
+}
+
+EventPageRequestManagerFactory::EventPageRequestManagerFactory()
+    : BrowserContextKeyedServiceFactory(
+          "EventPageRequestManager",
+          BrowserContextDependencyManager::GetInstance()) {
+  DependsOn(extensions::ProcessManagerFactory::GetInstance());
+}
+
+EventPageRequestManagerFactory::~EventPageRequestManagerFactory() = default;
+
+KeyedService* EventPageRequestManagerFactory::BuildServiceInstanceFor(
+    BrowserContext* context) const {
+  return new EventPageRequestManager(context);
+}
+
+}  // namespace media_router