Split PrefService into PrefService, PrefServiceSimple and PrefServiceSyncable.

chrome/browser/sync/glue/session_model_associator.h

Index: chrome/browser/sync/glue/session_model_associator.h
diff --git a/chrome/browser/sync/glue/session_model_associator.h b/chrome/browser/sync/glue/session_model_associator.h
index 31e28279602c32d4c18475c4857ebbe54a746639..85a04a78c4c034667629c3755c1e25a07a7c72a7 100644
--- a/chrome/browser/sync/glue/session_model_associator.h
+++ b/chrome/browser/sync/glue/session_model_associator.h
@@ -33,7 +33,7 @@
 #include "googleurl/src/gurl.h"
 #include "sync/internal_api/public/base/model_type.h"
 
-class Prefservice;
+class PrefServiceSyncable;
 class Profile;
 class ProfileSyncService;
 
@@ -509,7 +509,7 @@ class SessionModelAssociator
   Profile* const profile_;
 
   // Pref service. Used to persist the session sync guid. Weak pointer.
-  PrefService* const pref_service_;
+  PrefServiceSyncable* const pref_service_;
 
   DataTypeErrorHandler* error_handler_;