Voice search icon not touch explorable.

1. The overlaid DrawableStateProxyView was reacting to
   hover events essentially being touch explored so the
   views it coders did not get a chance to be touch
   explored. Now this view ignores hover events.

bug:6581924

Change-Id: I69d5ccaaf88b0f0ef661a237ce8a8abb8f65fa95
1 file changed