Gets hiding animations to work again

This broke when bounds changes was consolidated into
DesktopNativeWidgetAura::OnRootWindowHostResized. We can't resize the
child layers when this happens as otherwise we're going to force a
paint of the layers and thus the views. But at this point nothing is
valid and we don't want to paint anyway.

Also removing a call to Show() early on as it may trigger animations
that we don't want. A Show() at this time is before the creator has
had a chance to turn them off.

BUG=none
TEST=none
R=ananta@chromium.org

Review URL: https://codereview.chromium.org/27043007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229285 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229285