[rAC, OSX] Highlight errors on section change.

Errors weren't properly highlighted on section change, due to the fact
that the data to be validated (suggestion section vs. input section)
was picked based on visibility - but to avoid flicker, visibility is
only updated during performLayout.

New code queries flag for delayed visibility change instead.

BUG=312307
TEST=see instructions on bug
R=isherman@chromium.org

Review URL: https://codereview.chromium.org/108043008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241183 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241183