Implement PermissionService::GetNextPermissionChange.

chrome/browser/content_settings/permission_observer_factory.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 CHROME_BROWSER_CONTENT_SETTINGS_PERMISSION_OBSERVER_FACTORY_H_
+#define CHROME_BROWSER_CONTENT_SETTINGS_PERMISSION_OBSERVER_FACTORY_H_
+
+#include "base/memory/singleton.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+namespace content {
+class BrowserContext;
+}
+
+class PermissionObserver;
+class Profile;
+
+class PermissionObserverFactory : public BrowserContextKeyedServiceFactory {
+ public:
+  static PermissionObserver* GetForProfile(Profile* profile);
+  static PermissionObserverFactory* GetInstance();
+
+ private:
+  friend struct
+      DefaultSingletonTraits<PermissionObserverFactory>;
+
+  PermissionObserverFactory();
+  ~PermissionObserverFactory() override;
+
+  // BrowserContextKeyedBaseFactory methods:
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* profile) const override;
+  content::BrowserContext* GetBrowserContextToUse(
+      content::BrowserContext* context) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(PermissionObserverFactory);
+};
+
+#endif  // CHROME_BROWSER_CONTENT_SETTINGS_PERMISSION_OBSERVER_FACTORY_H_