Move AppWindowContents to apps component

This change also:
- moves some chrome specific logic from AppWindowContents
to the chrome shell window delegate
- gets rid of the app-only ShellWindow::Create so apps and
panels create shell windows in the same way
- moves registering with the registry to the constructor,
from constructor call sites.

BUG=159366

Review URL: https://chromiumcodereview.appspot.com/19272010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@211974 0039d316-1c4b-4281-b951-d872f2087c98
11 files changed