Enables the 'hotword not listening' icon in the search box.

This CL depends on https://codereview.chromium.org/145353016/

BUG=313904
R=xiyuan@chromium.org
TBR=oshima@chromium.org
TEST=manually

Review URL: https://codereview.chromium.org/149753002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248702 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248702