Add onChanged callback for chrome.sessions API.

chrome/browser/extensions/api/sessions/sessions_api.h

 // Copyright 2013 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_EXTENSIONS_API_SESSIONS_SESSIONS_API_H__
 #define CHROME_BROWSER_EXTENSIONS_API_SESSIONS_SESSIONS_API_H__
 
 #include <string>
 
 #include "chrome/browser/extensions/chrome_extension_function.h"
 #include "chrome/browser/sessions/tab_restore_service.h"
 #include "chrome/browser/sessions/tab_restore_service_observer.h"
 #include "chrome/common/extensions/api/sessions.h"
 #include "chrome/common/extensions/api/tabs.h"
 #include "chrome/common/extensions/api/windows.h"
+#include "extensions/browser/browser_context_keyed_api_factory.h"
+#include "extensions/browser/event_router.h"
 
 class Profile;
 
 namespace browser_sync {
 struct SyncedSession;
 }
 
 namespace extensions {
 
 class SessionId;
@@ skipping 46 matching lines @@
  private:
   void SetInvalidIdError(const std::string& invalid_id);
   void SetResultRestoredTab(const content::WebContents* contents);
   bool SetResultRestoredWindow(int window_id);
   bool RestoreMostRecentlyClosed(Browser* browser);
   bool RestoreLocalSession(const SessionId& session_id, Browser* browser);
   bool RestoreForeignSession(const SessionId& session_id,
                              Browser* browser);
 };
 
+class SessionsEventRouter : public TabRestoreServiceObserver {
+ public:
+  explicit SessionsEventRouter(Profile* profile);
+  virtual ~SessionsEventRouter();
+
+  // Observer callback for TabRestoreServiceObserver. Sends data on
+  // recently closed tabs to the javascript side of this page to
+  // display to the user.
+  virtual void TabRestoreServiceChanged(TabRestoreService* service) OVERRIDE;
+
+  // Observer callback to notice when our associated TabRestoreService
+  // is destroyed.

[not at google - send to devlin, 2014/03/21 11:03:06]

these are just overrides. the idiom is:

// TabRestoreServiceObserver implementation.
virtual void TabRestoreServiceChanged(..) OVERRIDE;
virtual void TabRestoreServiceDestroyed(..) OVERRIDE;

[wjywbs, 2014/03/21 19:45:33]

Should I remove these comments?

+  virtual void TabRestoreServiceDestroyed(TabRestoreService* service) OVERRIDE;
+
+ private:
+  Profile* profile_;
+
+  // TabRestoreService that we are observing.
+  TabRestoreService* tab_restore_service_;
+
+  DISALLOW_COPY_AND_ASSIGN(SessionsEventRouter);
+};
+
+class SessionsAPI : public BrowserContextKeyedAPI,
+                    public extensions::EventRouter::Observer {
+ public:
+  explicit SessionsAPI(content::BrowserContext* context);
+  virtual ~SessionsAPI();
+
+  // BrowserContextKeyedService implementation.
+  virtual void Shutdown() OVERRIDE;
+
+  // BrowserContextKeyedAPI implementation.
+  static BrowserContextKeyedAPIFactory<SessionsAPI>* GetFactoryInstance();
+
+  // EventRouter::Observer implementation.
+  virtual void OnListenerAdded(const extensions::EventListenerInfo& details)
+      OVERRIDE;
+
+ private:
+  friend class BrowserContextKeyedAPIFactory<SessionsAPI>;
+
+  content::BrowserContext* browser_context_;
+
+  // BrowserContextKeyedAPI implementation.
+  static const char* service_name() {
+    return "SessionsAPI";
+  }
+  static const bool kServiceIsNULLWhileTesting = true;
+
+  // Created lazily upon OnListenerAdded.
+  scoped_ptr<SessionsEventRouter> sessions_event_router_;
+
+  DISALLOW_COPY_AND_ASSIGN(SessionsAPI);
+};
+
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_SESSIONS_SESSIONS_API_H__