Moved GetUserDirectory() into mac_util.mm.

Made mac_util.mm and chrome_paths_mac.mm use GetUserDirectory().

Made firefox_importer_utils_mac.mm use PathService.

Added unittests for GetUserDirectory().

BUG=22045
TEST=trybots

Review URL: http://codereview.chromium.org/548123

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@37206 0039d316-1c4b-4281-b951-d872f2087c98
6 files changed