Pls wait for next release.

Please do this after M-67 branch.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9370fcdc31f68f5a4168df1150cca6f0728866f8

commit 9370fcdc31f68f5a4168df1150cca6f0728866f8
Author: Blake O'Hare <blakeo@chromium.org>
Date: Mon Jun 04 02:05:21 2018

Remove virtualKeyboardPrivate.setMode function

This is no longer actively being used and was replaced by
virtualKeyboardPrivate.setContainerBehavior

Removal of this was safe after the M67 branch.

Bug:  819095 
Change-Id: I289f6940521cbb9fbe75626e51f4cb70fccf8c29
Reviewed-on: https://chromium-review.googlesource.com/1082181
Reviewed-by: Toni Barzic <tbarzic@chromium.org>
Reviewed-by: Yuichiro Hanada <yhanada@chromium.org>
Commit-Queue: Blake O'Hare <blakeo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563986}
[modify] https://crrev.com/9370fcdc31f68f5a4168df1150cca6f0728866f8/extensions/browser/api/virtual_keyboard_private/virtual_keyboard_private_api.cc
[modify] https://crrev.com/9370fcdc31f68f5a4168df1150cca6f0728866f8/extensions/browser/api/virtual_keyboard_private/virtual_keyboard_private_api.h
[modify] https://crrev.com/9370fcdc31f68f5a4168df1150cca6f0728866f8/extensions/common/api/virtual_keyboard_private.json
[modify] https://crrev.com/9370fcdc31f68f5a4168df1150cca6f0728866f8/ui/keyboard/resources/inputview_adapter.js