[sync] WebContentsObserver based sessions notifications

chrome/browser/sync/sessions/sync_sessions_web_contents_router_factory.h

+// 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.
+
+#ifndef CHROME_BROWSER_SYNC_SESSIONS_SYNC_SESSIONS_WEB_CONTENTS_ROUTER_FACTORY_H_
+#define CHROME_BROWSER_SYNC_SESSIONS_SYNC_SESSIONS_WEB_CONTENTS_ROUTER_FACTORY_H_
+
+#include "base/macros.h"
+#include "components/keyed_service/content/browser_context_keyed_service_factory.h"
+
+class Profile;
+
+namespace base {
+template <typename T>
+struct DefaultSingletonTraits;
+}  // namespace base
+
+namespace sync_sessions {
+
+class SyncSessionsWebContentsRouter;
+
+class SyncSessionsWebContentsRouterFactory
+    : public BrowserContextKeyedServiceFactory {
+ public:
+  // Get the SyncSessionsWebContentsRouter service for |profile|, creating one
+  // if needed.
+  static SyncSessionsWebContentsRouter* GetForProfile(Profile* profile);
+
+  // Get the singleton instance of the factory.
+  static SyncSessionsWebContentsRouterFactory* GetInstance();
+
+  // Creates a SyncSessionsWebContentsRouter service for |context|.
+  static SyncSessionsWebContentsRouter* BuildSyncSessionsWebContentsRouter(
+      content::BrowserContext* context);
+
+ private:
+  friend struct base::DefaultSingletonTraits<
+      SyncSessionsWebContentsRouterFactory>;
+
+  SyncSessionsWebContentsRouterFactory();
+  ~SyncSessionsWebContentsRouterFactory() override;
+
+  // Overridden from BrowserContextKeyedServiceFactory.
+  KeyedService* BuildServiceInstanceFor(
+      content::BrowserContext* context) const override;
+
+  DISALLOW_COPY_AND_ASSIGN(SyncSessionsWebContentsRouterFactory);
+};
+
+}  // namespace sync_sessions
+
+#endif  // CHROME_BROWSER_SYNC_SESSIONS_SYNC_SESSIONS_WEB_CONTENTS_ROUTER_FACTORY_H_