bsd: refactor XDG bits of linux_util into a shared file.

base/base.gypi

Index: base/base.gypi
diff --git a/base/base.gypi b/base/base.gypi
index d57e58748c742970346426f56322cdf29a4546b9..5dfc760d97c6edab012f481628508d3b40292d5e 100644
--- a/base/base.gypi
+++ b/base/base.gypi
@@ -123,7 +123,7 @@
           'message_pump_win.cc',
           'message_pump_win.h',
           'mime_util.h',
-          'mime_util_linux.cc',
+          'mime_util_xdg.cc',
           'move.h',
           'native_library.h',
           'native_library_linux.cc',
@@ -279,6 +279,8 @@
           'worker_pool_mac.h',
           'worker_pool_mac.mm',
           'worker_pool_win.cc',
+          'xdg_util.h',
+          'xdg_util.cc',
         ],
         'include_dirs': [
           '..',
@@ -294,6 +296,7 @@
           [ 'OS != "linux" and OS != "freebsd" and OS != "openbsd" and OS != "solaris"', {
               'sources/': [
                 ['exclude', '/xdg_user_dirs/'],
+                ['exclude', '/xdg_[^/]*\\.cc$'],
                 ['exclude', '_nss\.cc$'],
               ],
               'sources!': [