[Android WebAPK] Make HostBrowserUtilsTest easier to understand

This CL makes HostBrowserUtilsTests easier to understand and modify.
Changes:
- Tests are now parameterized so that they run on both a bound and
  an unbound WebAPK.
- Comments for the tests are shorter and more concise.
- Global constants do not state whether the browser should be
  installed or not.

BUG=None

Change-Id: Ie1ce96892bf99001e07b42e3e4aaa4cdc53dfcb6
Reviewed-on: https://chromium-review.googlesource.com/c/1316364
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Reviewed-by: Xi Han <hanxi@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606236}
2 files changed