Add an API to unpack Zip files directly from and to file descriptors.

chrome/common/zip_internal.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 CHROME_COMMON_ZIP_INTERNAL_H_
 #define CHROME_COMMON_ZIP_INTERNAL_H_
 #pragma once
 
 #include <string>
 
 #include "third_party/zlib/contrib/minizip/unzip.h"
 #include "third_party/zlib/contrib/minizip/zip.h"
 
 // Utility functions and constants used internally for the zip file
 // library in the directory. Don't use them outside of the library.
 namespace zip {
 namespace internal {
 
 // Opens the given file name in UTF-8 for unzipping, with some setup for
 // Windows.
 unzFile OpenForUnzipping(const std::string& file_name_utf8);
 
+#if defined(OS_POSIX)
+// Opens the file referred to by |zip_fd| for unzipping.
+unzFile OpenFdForUnzipping(int zip_fd);
+#endif
+
 // Opens the given file name in UTF-8 for zipping, with some setup for
 // Windows. |append_flag| will be passed to zipOpen2().
 zipFile OpenForZipping(const std::string& file_name_utf8, int append_flag);
 
 const int kZipMaxPath = 256;
 const int kZipBufSize = 8192;
 
 }  // namespace internal
 }  // namespace zip
 
 #endif  // CHROME_COMMON_ZIP_INTERNAL_H_