Don't log empty FTP LIST responses as unknown server type.
Don't log empty FTP LIST responses as unknown server type.

The histograms will be more accurate after this change.

TEST=none
BUG=20335

Review URL: http://codereview.chromium.org/192038

git-svn-id: http://src.chromium.org/svn/trunk/src@25638 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 1064ee47a82644a7dba3d9df574be00e30ae14ac
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser