Fix homepage migration for users who never changed their settings.

chrome/browser/prefs/pref_service.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.
 
 // This provides a way to access the application's current preferences.
 
 // Chromium settings and storage represent user-selected preferences and
 // information and MUST not be extracted, overwritten or modified except
 // through Chromium defined APIs.
 
@@ skipping 249 matching lines @@
   double GetDouble(const char* path) const;
   std::string GetString(const char* path) const;
   FilePath GetFilePath(const char* path) const;
 
   // Returns the branch if it exists, or the registered default value otherwise.
   // Note that |path| must point to a registered preference. In that case, these
   // functions will never return NULL.
   const base::DictionaryValue* GetDictionary(const char* path) const;
   const base::ListValue* GetList(const char* path) const;
 
+  // Returns the value of the given preference, from the user pref store. If
+  // the preference is not set in the user pref store, returns NULL.
+  const base::Value* GetUserPrefValue(const char* path) const;
+
   // Removes a user pref and restores the pref to its default value.
   void ClearPref(const char* path);
 
   // If the path is valid (i.e., registered), update the pref value in the user
   // prefs.
   // To set the value of dictionary or list values in the pref tree use
   // Set(), but to modify the value of a dictionary or list use either
   // ListPrefUpdate or DictionaryPrefUpdate from scoped_user_pref_update.h.
   void Set(const char* path, const base::Value& value);
   void SetBoolean(const char* path, bool value);
@@ skipping 129 matching lines @@
 
   // Whether CreateIncognitoPrefService() or
   // CreatePrefServiceWithPerTabPrefStore() have been called to create a
   // "forked" PrefService.
   bool pref_service_forked_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefService);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_SERVICE_H_