Uses the hotword nexe from the CWS instead of the local package.

Note that it still uses its own JS handler rather than the extension's
JS code. This just replaces the location of nexe and data.

BUG=341716
R=xiyuan@chromium.org, miket@chromium.org, 
TEST=manually

Review URL: https://codereview.chromium.org/173123003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@253639 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 253639