The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e4bfb43fbb510010cf4feab2d7948d53210e07fe

commit e4bfb43fbb510010cf4feab2d7948d53210e07fe
Author: Ian Vollick <vollick@chromium.org>
Date: Tue Mar 27 03:19:26 2018

[vr] Display in-use permissions in WebVR on long press

With this change you can, via a long press, summon the in-use
permissions while in WebVR presentation.

In order to distinguish between the initial state when the
indicators are shown (web-vr-is-good-to-go/no-long-press)
from the state right after releasing the button, we need to
know the previous value in the binding, so I've introduced
a variant of the setter that can be passed the previous
value.

Bug:  825354 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_vr;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: Iad5696607e275169353695bb9d58d2b6a925478f
Reviewed-on: https://chromium-review.googlesource.com/978665
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Reviewed-by: Christopher Grant <cjgrant@chromium.org>
Commit-Queue: Ian Vollick <vollick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545952}
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/android/vr/vr_shell_gl.cc
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/android/vr/vr_shell_gl.h
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/vr/databinding/binding.h
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/vr/databinding/binding_unittest.cc
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/vr/model/controller_model.h
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/vr/ui.cc
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/vr/ui.h
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/vr/ui_scene_creator.cc
[modify] https://crrev.com/e4bfb43fbb510010cf4feab2d7948d53210e07fe/chrome/browser/vr/ui_unittest.cc

Verified in build 67.0.3389.0 canary.   Looks good.
Tests have been added to the Manual Test Plan.