GTK: Draw the correct omnibox state with new tab-to-traverse behavior.
This does everything but animate the trailing ">" icon from the right
side of the omnibox to the left when entering tab-to-search mode. The
TTS arrow indicator is now properly GTK themed, as well.
(Doing the animation is lower priority. It would require more
extensive refactoring that I don't have time for as I have code yellow work.)
TEST=all new tab-to-search behavior matches views sans animation.