Move and rename FdopenPlatformFile to file_util

base/platform_file_posix.cc

Index: base/platform_file_posix.cc
diff --git a/base/platform_file_posix.cc b/base/platform_file_posix.cc
index ff92b90a7c3c32fdbb8ad7b15adf59d3be3e44a1..cee1f611d11f5ed3937a73e9d46b7285781fb6e3 100644
--- a/base/platform_file_posix.cc
+++ b/base/platform_file_posix.cc
@@ -117,13 +117,6 @@ static PlatformFileError CallFctnlFlock(PlatformFile file, bool do_lock) {
 
 }  // namespace
 
-// NaCl doesn't implement system calls to open files directly.
-#if !defined(OS_NACL)
-FILE* FdopenPlatformFile(PlatformFile file, const char* mode) {
-  return fdopen(file, mode);
-}
-#endif  // !defined(OS_NACL)
-
 bool ClosePlatformFile(PlatformFile file) {
   base::ThreadRestrictions::AssertIOAllowed();
   return !IGNORE_EINTR(close(file));