Avoid fragmenting the heap too much while reconstructing the index.

net/disk_cache/simple/simple_util.cc

 // Copyright (c) 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.
 
 #include "net/disk_cache/simple/simple_util.h"
 
 #include <limits>
 
 #include "base/file_util.h"
 #include "base/format_macros.h"
@@ skipping 22 matching lines @@
   return hash_key_str;
 }
 
 std::string GetEntryHashKeyAsHexString(const std::string& key) {
   std::string hash_key_str =
       ConvertEntryHashKeyToHexString(GetEntryHashKey(key));
   DCHECK_EQ(kEntryHashKeyAsHexStringSize, hash_key_str.size());
   return hash_key_str;
 }
 
-bool GetEntryHashKeyFromHexString(const std::string& hash_key,
+bool GetEntryHashKeyFromHexString(const base::StringPiece& hash_key,
                                   uint64* hash_key_out) {
   if (hash_key.size() != kEntryHashKeyAsHexStringSize) {
     return false;
   }
   return base::HexStringToUInt64(hash_key, hash_key_out);
 }
 
 uint64 GetEntryHashKey(const std::string& key) {
   union {
     unsigned char sha_hash[base::kSHA1Length];
@@ skipping 37 matching lines @@
   base::PlatformFileInfo file_info;
   if (!file_util::GetFileInfo(path, &file_info))
     return false;
   *out_mtime = file_info.last_modified;
   return true;
 }
 
 }  // namespace simple_backend
 
 }  // namespace disk_cache