~Browser: Don't create TabRestoreService on exit.

chrome/browser/sessions/session_service_factory.h

 // Copyright (c) 2011 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_SESSIONS_SESSION_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_SESSIONS_SESSION_SERVICE_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "chrome/browser/profiles/profile_keyed_service_factory.h"
 #include "chrome/browser/sessions/session_service.h"
 
 class Profile;
 
 // Singleton that owns all SessionServices and associates them with
 // Profiles. Listens for the Profile's destruction notification and cleans up
 // the associated SessionService.
 class SessionServiceFactory : public ProfileKeyedServiceFactory {
  public:
   // Returns the session service for |profile|. This may return NULL. If this
   // profile supports a session service (it isn't incognito), and the session
   // service hasn't yet been created, this forces creation of the session
   // service.
   //
-  // This returns NULL in two situations: the profile is incognito, or the
-  // session service has been explicitly shutdown (browser is exiting). Callers
-  // should always check the return value for NULL.
+  // This returns NULL if the profile is incognito. Callers should always check
+  // the return value for NULL.
   static SessionService* GetForProfile(Profile* profile);
 
   // Returns the session service for |profile|, but do not create it if it
-  // doesn't exist.
+  // doesn't exist. This returns NULL if the profile is incognito or if session
+  // service has been explicitly shutdown (browser is exiting). Callers should
+  // always check the return value for NULL.
   static SessionService* GetForProfileIfExisting(Profile* profile);
 
   // If |profile| has a session service, it is shut down. To properly record the
   // current state this forces creation of the session service, then shuts it
   // down.
   static void ShutdownForProfile(Profile* profile);
 
 #if defined(UNIT_TEST)
   // For test use: force setting of the session service for a given profile.
   // This will delete a previous session service for this profile if it exists.
@@ skipping 13 matching lines @@
   virtual ~SessionServiceFactory();
 
   // ProfileKeyedServiceFactory:
   virtual ProfileKeyedService* BuildServiceInstanceFor(
       Profile* profile) const OVERRIDE;
   virtual bool ServiceIsCreatedWithProfile() OVERRIDE;
   virtual bool ServiceIsNULLWhileTesting() OVERRIDE;
 };
 
 #endif  // CHROME_BROWSER_SESSIONS_SESSION_SERVICE_FACTORY_H_