Fix the hash generation algorithm to be consistent with prior implementation.

chrome/browser/prefs/pref_hash_calculator.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_CALCULATOR_H_
 #define CHROME_BROWSER_PREFS_PREF_HASH_CALCULATOR_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 21 matching lines @@
   std::string Calculate(const std::string& path, const base::Value* value)
       const;
 
   // Validates the provided preference hash using current and legacy hashing
   // algorithms.
   ValidationResult Validate(const std::string& path,
                             const base::Value* value,
                             const std::string& hash) const;
 
  private:
-  // Calculate a hash using a deprecated hash algorithm. For validating old
-  // hashes during migration.
-  std::string CalculateLegacyHash(const std::string& path,
-                                  const base::Value* value) const;
+  // Concatenates |device_id_|, |path|, and |value| to give the hash input.
+  std::string GetMessage(const std::string& path,
+                         const base::Value* value) const;
 
   std::string seed_;
   std::string device_id_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefHashCalculator);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_HASH_CALCULATOR_H_