Revert 229507 "aura: Allow creating content_shell without views."

Speculative. All windows bots on the main waterfall except for the clobber
builder started timing out during compile during a window that had only this
change and two test-only changes in the range.

> aura: Allow creating content_shell without views.
> 
> This builds content_shell with use_aura=1 and toolkit_views=0.
> 
> BUG=none
> R=derat@chromium.org, jamescook@chromium.org, jochen@chromium.org
> 
> Review URL: https://codereview.chromium.org/26695007

TBR=sadrul@chromium.org

Review URL: https://codereview.chromium.org/30413002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229521 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229521