referrer_charset is a lie. It's really the user's default_charset.

net/base/net_util.h

 // Copyright (c) 2012 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_BASE_NET_UTIL_H_
 #define NET_BASE_NET_UTIL_H_
 #pragma once
 
 #include "build/build_config.h"
 
@@ skipping 116 matching lines @@
 NET_EXPORT std::string GetHostOrSpecFromURL(const GURL& url);
 
 // Return the value of the HTTP response header with name 'name'.  'headers'
 // should be in the format that URLRequest::GetResponseHeaders() returns.
 // Returns the empty string if the header is not found.
 NET_EXPORT std::string GetSpecificHeader(const std::string& headers,
                                          const std::string& name);
 
 // TODO(abarth): Move these functions to http_content_disposition.cc.
 bool DecodeFilenameValue(const std::string& input,
-                         const std::string& referrer_charset,
+                         const std::string& default_charset,
                          std::string* output);
 bool DecodeExtValue(const std::string& value, std::string* output);
 
 // Converts the given host name to unicode characters. This can be called for
 // any host name, if the input is not IDN or is invalid in some way, we'll just
 // return the ASCII source so it is still usable.
 //
 // The input should be the canonicalized ASCII host name from GURL. This
 // function does NOT accept UTF-8!
 //
@@ skipping 54 matching lines @@
                                                 base::Time modified);
 
 // If text starts with "www." it is removed, otherwise text is returned
 // unmodified.
 NET_EXPORT string16 StripWWW(const string16& text);
 
 // Generates a filename using the first successful method from the following (in
 // order):
 //
 // 1) The raw Content-Disposition header in |content_disposition| (as read from
-//    the network.  |referrer_charset| is used as described in the comment for
+//    the network.  |default_charset| is used as described in the comment for
 //    GetFileNameFromCD().
 // 2) |suggested_name| if specified.  |suggested_name| is assumed to be in
 //    UTF-8.
-// 3) The filename extracted from the |url|.  |referrer_charset| will be used to
+// 3) The filename extracted from the |url|.  |default_charset| will be used to
 //    interpret the URL if there are non-ascii characters.
 // 4) |default_name|.  If non-empty, |default_name| is assumed to be a filename
 //    and shouldn't contain a path.  |default_name| is not subject to validation
 //    or sanitization, and therefore shouldn't be a user supplied string.
 // 5) The hostname portion from the |url|
 //
 // Then, leading and trailing '.'s will be removed.  On Windows, trailing spaces
 // are also removed.  The string "download" is the final fallback if no filename
 // is found or the filename is empty.
 //
 // Any illegal characters in the filename will be replaced by '-'.  If the
 // filename doesn't contain an extension, and a |mime_type| is specified, the
 // preferred extension for the |mime_type| will be appended to the filename.
 // The resulting filename is then checked against a list of reserved names on
 // Windows.  If the name is reserved, an underscore will be prepended to the
 // filename.
 //
 // Note: |mime_type| should only be specified if this function is called from a
 // thread that allows IO.
 NET_EXPORT string16 GetSuggestedFilename(const GURL& url,
                                          const std::string& content_disposition,
-                                         const std::string& referrer_charset,
+                                         const std::string& default_charset,
                                          const std::string& suggested_name,
                                          const std::string& mime_type,
                                          const std::string& default_name);
 
 // Similar to GetSuggestedFilename(), but returns a FilePath.
 NET_EXPORT FilePath GenerateFileName(const GURL& url,
                                      const std::string& content_disposition,
-                                     const std::string& referrer_charset,
+                                     const std::string& default_charset,
                                      const std::string& suggested_name,
                                      const std::string& mime_type,
                                      const std::string& default_name);
 
 // Ensures that the filename and extension is safe to use in the filesystem.
 //
 // Assumes that |file_path| already contains a valid path or file name.  On
 // Windows if the extension causes the file to have an unsafe interaction with
 // the shell (see net_util::IsShellIntegratedExtension()), then it will be
 // replaced by the string 'download'.  If |file_path| doesn't contain an
@@ skipping 210 matching lines @@
 
 // Returns list of network interfaces except loopback interface. If an
 // interface has more than one address, a separate entry is added to
 // the list for each address.
 // Can be called only on a thread that allows IO.
 NET_EXPORT bool GetNetworkList(NetworkInterfaceList* networks);
 
 }  // namespace net
 
 #endif  // NET_BASE_NET_UTIL_H_