NNTP: Only show completed downloads.
NNTP: Only show completed downloads.

BUG=16719

TEST=Download a big file (http://www.thinkbroadband.com/download.html
has good files for testing downloads) and make sure that that cancelled
and in progress downloads are not shown on the new tab page.


Review URL: http://codereview.chromium.org/149685

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@20780 0039d316-1c4b-4281-b951-d872f2087c98

gavinp/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,adobe/chromium,adobe/chromium,ropik/chromium,adobe/chromium,Crystalnix/house-of-life-chromium,ropik/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,ropik/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,adobe/chromium,ropik/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,Crystalnix/house-of-life-chromium,adobe/chromium,Crystalnix/house-of-life-chromium,gavinp/chromium,yitian134/chromium,adobe/chromium,adobe/chromium,yitian134/chromium,yitian134/chromium,Crystalnix/house-of-life-chromium,yitian134/chromium,gavinp/chromium,gavinp/chromium,ropik/chromium,gavinp/chromium,adobe/chromium,Crystalnix/house-of-life-chromium