Fixes a crash when xdg_mime library is unable to handle a long file path.

      BUG=48733
TEST=None

Review URL: http://codereview.chromium.org/2980002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@52130 0039d316-1c4b-4281-b951-d872f2087c98