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

chrome/common/zip_internal.cc

Index: chrome/common/zip_internal.cc
diff --git a/chrome/common/zip_internal.cc b/chrome/common/zip_internal.cc
index ddcfd00a360fb1d01383d27f04aa75669e92d7f5..fd46a9b8a5c450e243de31f7f09eaa2ec61ee975 100644
--- a/chrome/common/zip_internal.cc
+++ b/chrome/common/zip_internal.cc
@@ -81,6 +81,15 @@ unzFile OpenForUnzipping(const std::string& file_name_utf8) {
   return unzOpen2(file_name_utf8.c_str(), zip_func_ptrs);
 }
 
+#if defined(OS_POSIX)
+unzFile OpenFdForUnzipping(int zip_fd) {
+  zlib_filefunc_def zip_funcs;
+  fill_fdopen_filefunc(&zip_funcs, zip_fd);
+  // Passing dummy "fd" filename to zlib.
+  return unzOpen2("fd", &zip_funcs);
+}
+#endif
+
 zipFile OpenForZipping(const std::string& file_name_utf8, int append_flag) {
   zlib_filefunc_def* zip_func_ptrs = NULL;
 #if defined(OS_WIN)