Move preference MACs to the protected preference stores.

chrome/browser/prefs/pref_hash_store.h

Index: chrome/browser/prefs/pref_hash_store.h
diff --git a/chrome/browser/prefs/pref_hash_store.h b/chrome/browser/prefs/pref_hash_store.h
index a6d97277b70b61acf57a3e3a9d64dd79bd2be7db..157a04c2b8bb5007e1211b924f0d7f4948e2c5fa 100644
--- a/chrome/browser/prefs/pref_hash_store.h
+++ b/chrome/browser/prefs/pref_hash_store.h
@@ -19,6 +19,13 @@ class PrefHashStore {
   // of checks/transformations on the hash store.
   virtual scoped_ptr<PrefHashStoreTransaction> BeginTransaction() = 0;
 
+  // Determines if the hash store has been initialized (contains any values).
+  virtual bool IsInitialized() const = 0;
+
+  // Clears the contents of this PrefHashStore. |IsInitialized()| will return
+  // false after this call.
+  virtual void Reset() = 0;
+
   // Commits this store to disk if it has changed since the last call to this
   // method.
   virtual void CommitPendingWrite() = 0;