Move bit_cast from base/macros.h to its own header

net/disk_cache/blockfile/disk_format_v3.h

 // Copyright (c) 2011 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.
 
 // The cache is stored on disk as a collection of block-files, plus an index
 // plus a collection of external files.
 //
 // Any data blob bigger than kMaxBlockSize (disk_cache/addr.h) will be stored in
 // a separate file named f_xxx where x is a hexadecimal number. Shorter data
 // will be stored as a series of blocks on a block-file. In any case, CacheAddr
@@ skipping 28 matching lines @@
 // backup files for cache bitmaps, used to detect entries out of date.
 //
 // Although cache files are to be consumed on the same machine that creates
 // them, if files are to be moved accross machines, little endian storage is
 // assumed.
 
 #ifndef NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_
 #define NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_
 
 #include <stdint.h>
+#include <string.h>
 
 #include "net/disk_cache/blockfile/disk_format_base.h"
 
 namespace disk_cache {
 
 const int kBaseTableLen = 0x400;
 const uint32_t kIndexMagicV3 = 0xC103CAC3;
 const uint32_t kVersion3 = 0x30000;  // Version 3.0.
 
 // Flags for a given cache.
@@ skipping 179 matching lines @@
   int32_t key_len;
   uint64_t last_access_time;
   uint32_t long_hash[5];
   uint32_t self_hash;
 };
 static_assert(sizeof(ShortEntryRecord) == 48, "bad ShortEntryRecord");
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_BLOCKFILE_DISK_FORMAT_V3_H_