Minor simplification of shell startup process

BUG=273142
R=mukai@chromium.org

Review URL: https://codereview.chromium.org/27709004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229387 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229387