Move extension install to after .crx download completes

This was resulting in some situations where we attempted to unpack the .crx while its file was still in use by the download manager.

BUG=15881
R=mpcomplete

Review URL: http://codereview.chromium.org/149161

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@20083 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed