Use xdg_user_dir_lookup to lookup directories.

chrome/third_party/xdg_user_dirs/xdg_user_dir_lookup.h

+/*
+  This file is not licenced under the GPL like the rest of the code.
+  Its is under the MIT license, to encourage reuse by cut-and-paste.
+
+  Copyright (c) 2007 Red Hat, inc
+
+  Permission is hereby granted, free of charge, to any person
+  obtaining a copy of this software and associated documentation files
+  (the "Software"), to deal in the Software without restriction,
+  including without limitation the rights to use, copy, modify, merge,
+  publish, distribute, sublicense, and/or sell copies of the Software,
+  and to permit persons to whom the Software is furnished to do so,
+  subject to the following conditions: 
+
+  The above copyright notice and this permission notice shall be
+  included in all copies or substantial portions of the Software. 
+
+  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+  SOFTWARE.
+*/
+
+#ifndef CHROME_THIRD_PARTY_XDG_USER_DIRS_XDG_USER_DIR_LOOKUP_H_
+#define CHROME_THIRD_PARTY_XDG_USER_DIRS_XDG_USER_DIR_LOOKUP_H_
+
+char* xdg_user_dir_lookup(const char *type);
+
+#endif  // CHROME_THIRD_PARTY_XDG_USER_DIRS_XDG_USER_DIR_LOOKUP_H_