Now takes browser pointer instead of a location bar pointer.

Chromium change:

https://chromium.googlesource.com/chromium/src/+/ad9765ab97dfb00c188a331852abcbf40e818a14

commit ad9765ab97dfb00c188a331852abcbf40e818a14
Author: Evan Stade <estade@chromium.org>
Date:   Tue Jul 2 17:02:41 2019 +0000

    Remove NOTIFICATION_AUTOCOMPLETE_CONTROLLER_RESULT_READY

    This was only used in tests. Those tests can instead use
    OmniboxControllerEmitter::Observer.

    This CL also combines the OmniboxApiTests that are browser tests with
    the ones that are interactive ui tests. They were split rather sloppily,
    with a common base class declared and defined in a header file they both
    included (but not mentioned in any BUILD.gn). Most of the affected tests
    are actually disabled anyway. Now they're all interactive ui tests.

    Bug: 268984