Close the download shelf if it's showing, when showing the downloads tab.
Close the download shelf if it's showing, when showing the downloads tab.

BUG=77716
TEST=trybots, manual testing

Review URL: http://codereview.chromium.org/6794011

git-svn-id: http://src.chromium.org/svn/trunk/src@80334 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 63629e4602bfef876b3878040d46aad601b9549e
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