Split PrefService into PrefService, PrefServiceSimple and PrefServiceSyncable.

chrome/browser/prefs/browser_prefs.h

Index: chrome/browser/prefs/browser_prefs.h
diff --git a/chrome/browser/prefs/browser_prefs.h b/chrome/browser/prefs/browser_prefs.h
index 93219e711014b79da5d52375ad657f9e4a33f6d7..42862a16a3aa0d0829d6c6e48225d6883c99b96c 100644
--- a/chrome/browser/prefs/browser_prefs.h
+++ b/chrome/browser/prefs/browser_prefs.h
@@ -6,13 +6,15 @@
 #define CHROME_BROWSER_PREFS_BROWSER_PREFS_H_
 
 class PrefService;
+class PrefServiceSimple;
+class PrefServiceSyncable;
 class Profile;
 
 namespace chrome {
 
 // Makes the PrefService objects aware of all the prefs.
-void RegisterLocalState(PrefService* local_state);
-void RegisterUserPrefs(PrefService* user_prefs);
+void RegisterLocalState(PrefServiceSimple* local_state);
+void RegisterUserPrefs(PrefServiceSyncable* user_prefs);
 
 // Migrates prefs from |local_state| to |profile|'s pref store.
 void MigrateBrowserPrefs(Profile* profile, PrefService* local_state);