Split PrefService into PrefService, PrefServiceSimple and PrefServiceSyncable.

chrome/browser/chromeos/display/display_preferences.h

Index: chrome/browser/chromeos/display/display_preferences.h
diff --git a/chrome/browser/chromeos/display/display_preferences.h b/chrome/browser/chromeos/display/display_preferences.h
index be358a1021acb3d78fada214bbb852ed6b18d5ac..615ce570bc1aadc8bd32783e0668820390e807e0 100644
--- a/chrome/browser/chromeos/display/display_preferences.h
+++ b/chrome/browser/chromeos/display/display_preferences.h
@@ -7,7 +7,8 @@
 
 #include "base/basictypes.h"
 
-class PrefService;
+class PrefServiceSimple;
+
 namespace gfx {
 class Display;
 class Insets;
@@ -17,7 +18,7 @@ namespace chromeos {
 
 // Registers the prefs associated with display settings and stored
 // into Local State.
-void RegisterDisplayLocalStatePrefs(PrefService* local_state);
+void RegisterDisplayLocalStatePrefs(PrefServiceSimple* local_state);
 
 // Sets or updates the display layout data to the specified |display| and
 // |pref_service|.