Revert 247151 "Cleanup of windows launch code"

> Cleanup of windows launch code
> 
> The windows startup code was handling aura and non-aura cases which
> require different startup logic in metro (immersive mode). Since we
> don't support the non-Aura logic we can get rid of a lot of code.
> 
> Tbring gab for the installer constant addition.
> 
> R=ananta@chromium.org, scottmg@chromium.org
> TBR=gab
> BUG=none
> 
> Review URL: https://codereview.chromium.org/142473002

TBR=cpu@chromium.org

Review URL: https://codereview.chromium.org/140123006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247156 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247156