Fix a race condition opening a downloaded file.
Fix a race condition opening a downloaded file.

There is a potential race condition where we attempt
to open, via the shell, a fast completing download
before it has been renamed. This fix posts the rename
operation before calling DownloadFinished, which posts
the shell open.

BUG=3954 (http://crbug.com/3954)

Review URL: http://codereview.chromium.org/42685

git-svn-id: http://src.chromium.org/svn/trunk/src@12676 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: ad4ab5e722bdc20be6786811082b1fc258e148ca
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