Split PrefService into PrefService, PrefServiceSimple and PrefServiceSyncable.

chrome/browser/download/download_prefs.h

Index: chrome/browser/download/download_prefs.h
diff --git a/chrome/browser/download/download_prefs.h b/chrome/browser/download/download_prefs.h
index 95d581d3b4551e970d0bd7cc4cd2d242a82226ca..e8dfefbdb27a23f21ebb5c4e379dbfdefe4ea5fd 100644
--- a/chrome/browser/download/download_prefs.h
+++ b/chrome/browser/download/download_prefs.h
@@ -10,6 +10,7 @@
 #include "base/file_path.h"
 #include "base/prefs/public/pref_member.h"
 
+class PrefServiceSyncable;
 class Profile;
 
 namespace content {
@@ -23,7 +24,7 @@ class DownloadPrefs {
   explicit DownloadPrefs(Profile* profile);
   ~DownloadPrefs();
 
-  static void RegisterUserPrefs(PrefServiceBase* prefs);
+  static void RegisterUserPrefs(PrefServiceSyncable* prefs);
 
   // Returns the DownloadPrefs corresponding to the given DownloadManager
   // or BrowserContext.