Remove dead code, GetDataMimeType

base/nix/mime_util_xdg.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 BASE_NIX_MIME_UTIL_XDG_H_
 #define BASE_NIX_MIME_UTIL_XDG_H_
 
 #include <string>
 
 #include "base/base_export.h"
@@ skipping 12 matching lines @@
 // have to exist.  This means that the function does not work for directories
 // (i.e. |filepath| is assumed to be a path to a file).
 //
 // Note that this function might need to read from disk the mime-types data
 // provided by the OS.  Therefore this function should not be called from
 // threads that disallow IO via base::ThreadRestrictions::SetIOAllowed(false).
 //
 // If the mime type is unknown, this will return application/octet-stream.
 BASE_EXPORT std::string GetFileMimeType(const FilePath& filepath);
 
-// Get the mime type for a byte vector.
-BASE_EXPORT std::string GetDataMimeType(const std::string& data);
-
 }  // namespace nix
 }  // namespace base
 
 #endif  // BASE_NIX_MIME_UTIL_XDG_H_