Move preference MACs to the protected preference stores.

chrome/browser/prefs/pref_hash_store.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_PREFS_PREF_HASH_STORE_H_
 #define CHROME_BROWSER_PREFS_PREF_HASH_STORE_H_
 
 #include "base/memory/scoped_ptr.h"
 
 class PrefHashStoreTransaction;
 
 // Stores hashes of and verifies preference values via
 // PrefHashStoreTransactions.
 class PrefHashStore {
  public:
   virtual ~PrefHashStore() {}
 
   // Returns a PrefHashStoreTransaction which can be used to perform a series
   // 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;
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_HASH_STORE_H_