Fix homepage migration for users who never changed their settings.

chrome/browser/prefs/session_startup_pref.h

 // Copyright (c) 2012 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_PREFS_SESSION_STARTUP_PREF_H__
 #define CHROME_BROWSER_PREFS_SESSION_STARTUP_PREF_H__
 #pragma once
 
 #include <vector>
 
@@ skipping 28 matching lines @@
   // Returns the default value for |type|.
   static Type GetDefaultStartupType();
 
   // What should happen on startup for the specified profile.
   static void SetStartupPref(Profile* profile, const SessionStartupPref& pref);
   static void SetStartupPref(PrefService* prefs,
                              const SessionStartupPref& pref);
   static SessionStartupPref GetStartupPref(Profile* profile);
   static SessionStartupPref GetStartupPref(PrefService* prefs);
 
+  // Migrates from "Open the home page" to "Open the following URLs", and sets
+  // the list of URLs to a one-item list containing the user's homepage.
+  static void MigrateIfNecessary(PrefService* prefs);
+
   // Whether the startup type and URLs are managed via policy.
   static bool TypeIsManaged(PrefService* prefs);
   static bool URLsAreManaged(PrefService* prefs);
 
   // Converts an integer pref value to a SessionStartupPref::Type.
   static SessionStartupPref::Type PrefValueToType(int pref_value);
 
   // Returns |true| if a change to startup type or URLS was detected by
   // ProtectorService.
   static bool DidStartupPrefChange(Profile* profile);
 
   // Returns the protected backup of startup type and URLS.
   static SessionStartupPref GetStartupPrefBackup(Profile* profile);
 
   explicit SessionStartupPref(Type type);
 
   ~SessionStartupPref();
 
   // What to do on startup.
   Type type;
 
   // The URLs to restore. Only used if type == URLS.
   std::vector<GURL> urls;
 };
 
 #endif  // CHROME_BROWSER_PREFS_SESSION_STARTUP_PREF_H__