Move preference MACs to the protected preference stores.

base/prefs/json_pref_store_unittest.cc

Index: base/prefs/json_pref_store_unittest.cc
diff --git a/base/prefs/json_pref_store_unittest.cc b/base/prefs/json_pref_store_unittest.cc
index 4c9c847708f5f2d3f9845759bfffb7598b68e832..2b4a9e8e7e7ab0846478e70c9c923c946f5fbe86 100644
--- a/base/prefs/json_pref_store_unittest.cc
+++ b/base/prefs/json_pref_store_unittest.cc
@@ -40,7 +40,7 @@ class InterceptingPrefFilter : public PrefFilter {
       scoped_ptr<base::DictionaryValue> pref_store_contents) OVERRIDE;
   virtual void FilterUpdate(const std::string& path) OVERRIDE {}
   virtual void FilterSerializeData(
-      const base::DictionaryValue* pref_store_contents) OVERRIDE {}
+      base::DictionaryValue* pref_store_contents) OVERRIDE {}
 
   bool has_intercepted_prefs() const { return intercepted_prefs_ != NULL; }