Switch to appropriate UI mode when Assistant interaction in progress.

Previously, if a text query were initiated via deeplink and the UI
was visible but not in main/embedded UI mode, the interaction would
not be visible to the user.

Bug: b:113278359
Change-Id: I1f65e0955df688cc08f1b511d09d6bf99a9a55a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1566725
Commit-Queue: David Black <dmblack@google.com>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Tao Wu <wutao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652691}
11 files changed