Refactor Pickle Read methods to use higher performance PickleIterator.

chrome/browser/sessions/compress_data_helper.h

 // Copyright (c) 2012 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_SESSIONS_COMPRESS_DATA_HELPER_H_
 #define CHROME_BROWSER_SESSIONS_COMPRESS_DATA_HELPER_H_
 #pragma once
 
 #include "base/basictypes.h"
 
 #include <string>
 
 class Pickle;
+class PickleIterator;
 
 class CompressDataHelper {
  public:
   // Compresses and writes |str| into |pickle|. |str| may contain NULL
   // charaters.
   static void CompressAndWriteStringToPickle(const std::string& str,
                                              int max_bytes,
                                              Pickle* pickle,
                                              int* bytes_written);
 
   // Reads and decompresses a string from |pickle| and saves it to |str|. |iter|
   // indicates the position of the data. The same iterator is used by
   // Pickle::Read* functions.
   static bool ReadAndDecompressStringFromPickle(const Pickle& pickle,
-                                                void** iter,
+                                                PickleIterator* iter,
                                                 std::string* str);
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(CompressDataHelper);
 };
 
 #endif  // CHROME_BROWSER_SESSIONS_COMPRESS_DATA_HELPER_H_