The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6b0313ea484b134a3157f2fbfbbb550d271de405

commit 6b0313ea484b134a3157f2fbfbbb550d271de405
Author: Christopher Grant <cjgrant@chromium.org>
Date: Tue Jan 09 16:31:01 2018

VR: Prevent inline autocomplete from omnibox text

The omnibox does not yet support inline autocomplete matches (meaning
that the user doesn't see in-line text indicating what they'll get if
they press Enter).  Therefore, to keep the user from being confused
about where they land after pressing Enter, tell the
AutocompleteController to prevent inline matches.

This essentially ensures that the top (default) match is always
something that can be obviously derived from what they've typed.
Usually that's a search, or a URL if they've typed a valid URL.

Along the way, sever the VR AutocompleteController from direct knowledge
of the UI it's feeding - there was never any need for that.

BUG= 799171 
R=ymalik

Change-Id: Ic109e9aa6c5a2318deb8de894fb9559de85b9ed3
Reviewed-on: https://chromium-review.googlesource.com/854622
Reviewed-by: Yash Malik <ymalik@chromium.org>
Commit-Queue: Christopher Grant <cjgrant@chromium.org>
Cr-Commit-Position: refs/heads/master@{#528015}
[modify] https://crrev.com/6b0313ea484b134a3157f2fbfbbb550d271de405/chrome/browser/android/vr_shell/autocomplete_controller.cc
[modify] https://crrev.com/6b0313ea484b134a3157f2fbfbbb550d271de405/chrome/browser/android/vr_shell/autocomplete_controller.h
[modify] https://crrev.com/6b0313ea484b134a3157f2fbfbbb550d271de405/chrome/browser/android/vr_shell/vr_shell.cc

Added test case "Default Search behavior on Enter" to "VR Browsing: Omnibox text entry manual test plan" to cover Enter behavior.  It covers both basic Search string resulting in Google Search and URL strings resulting it navigation to specific URL page.