Refactor Pickle Read methods to use higher performance PickleIterator.

webkit/fileapi/file_system_usage_cache.cc

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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.
 
 #include "webkit/fileapi/file_system_usage_cache.h"
 
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/pickle.h"
 
 namespace fileapi {
@@ skipping 112 matching lines @@
 int64 FileSystemUsageCache::Read(const FilePath& usage_file_path,
                                  bool* is_valid,
                                  uint32* dirty) {
   char buffer[kUsageFileSize];
   const char *header;
   DCHECK(!usage_file_path.empty());
   if (kUsageFileSize !=
       file_util::ReadFile(usage_file_path, buffer, kUsageFileSize))
     return -1;
   Pickle read_pickle(buffer, kUsageFileSize);
-  void* iter = NULL;
+  PickleIterator iter(read_pickle);
   int64 fs_usage;
 
   if (!read_pickle.ReadBytes(&iter, &header, kUsageFileHeaderSize) ||
       !read_pickle.ReadBool(&iter, is_valid) ||
       !read_pickle.ReadUInt32(&iter, dirty) ||
       !read_pickle.ReadInt64(&iter, &fs_usage))
     return -1;
 
   if (header[0] != kUsageFileHeader[0] ||
       header[1] != kUsageFileHeader[1] ||
@@ skipping 25 matching lines @@
   if (bytes_written != kUsageFileSize)
     return -1;
 
   if (file_util::ReplaceFile(temporary_usage_file_path, usage_file_path))
     return bytes_written;
   else
     return -1;
 }
 
 }  // namespace fileapi