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

net/disk_cache/blockfile/bitmap.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.
 
 #ifndef NET_DISK_CACHE_BLOCKFILE_BITMAP_H_
 #define NET_DISK_CACHE_BLOCKFILE_BITMAP_H_
 
 #include <stdint.h>
+#include <string.h>
 
 #include "base/macros.h"
 #include "net/base/net_export.h"
 
 namespace disk_cache {
 
 // This class provides support for simple maps of bits.
 class NET_EXPORT_PRIVATE Bitmap {
  public:
   Bitmap() : map_(NULL), num_bits_(0), array_size_(0), alloc_(false) {}
@@ skipping 110 matching lines @@
   int num_bits_;          // The upper bound of the bitmap.
   int array_size_;        // The physical size (in uint32s) of the bitmap.
   bool alloc_;            // Whether or not we allocated the memory.
 
   DISALLOW_COPY_AND_ASSIGN(Bitmap);
 };
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_BLOCKFILE_BITMAP_H_