The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2537fa873c33c1c2597b2f03d7a15d7c88d1da3e

commit 2537fa873c33c1c2597b2f03d7a15d7c88d1da3e
Author: Michael Thiessen <mthiesse@google.com>
Date: Fri Jun 02 19:46:07 2017

VR: Use system back button behaviour while in ChromeTabbedActivity.

This allows us to behave the same way CTA does when hitting the back button,
which includes closing tabs opened by links. However, we disable exiting
chrome when the back stack is exhausted.

This is important because we don't support manual tab management yet in VR,
so we don't want users to get stuck after a link opens in a new tab.

Bug:  728725 
Change-Id: I5c042bd9f902fdee3db56451de97fe944dcf293d
Reviewed-on: https://chromium-review.googlesource.com/519802
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Reviewed-by: Yash Malik <ymalik@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#476760}
[modify] https://crrev.com/2537fa873c33c1c2597b2f03d7a15d7c88d1da3e/chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity.java
[modify] https://crrev.com/2537fa873c33c1c2597b2f03d7a15d7c88d1da3e/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellImpl.java
[modify] https://crrev.com/2537fa873c33c1c2597b2f03d7a15d7c88d1da3e/chrome/browser/android/vr_shell/ui_elements/url_bar.cc
[modify] https://crrev.com/2537fa873c33c1c2597b2f03d7a15d7c88d1da3e/chrome/browser/android/vr_shell/ui_elements/url_bar.h

Your change meets the bar and is auto-approved for M60. Please go ahead and merge the CL to branch 3112 manually. Please contact milestone owner if you have questions.
Owners: amineer@(Android), cmasso@(iOS), josafat@(ChromeOS), bustamante@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2c81bbb26501c9f5dfa48abefd9c8b80dd161e5c

commit 2c81bbb26501c9f5dfa48abefd9c8b80dd161e5c
Author: Michael Thiessen <mthiesse@google.com>
Date: Mon Jun 05 14:35:51 2017

VR: Use system back button behaviour while in ChromeTabbedActivity.

This allows us to behave the same way CTA does when hitting the back button,
which includes closing tabs opened by links. However, we disable exiting
chrome when the back stack is exhausted.

This is important because we don't support manual tab management yet in VR,
so we don't want users to get stuck after a link opens in a new tab.

Bug:  728725 
Change-Id: I5c042bd9f902fdee3db56451de97fe944dcf293d
Reviewed-on: https://chromium-review.googlesource.com/519802
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Reviewed-by: Yash Malik <ymalik@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#476760}
Review-Url: https://codereview.chromium.org/2924593002 .
Cr-Commit-Position: refs/branch-heads/3112@{#151}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}

[modify] https://crrev.com/2c81bbb26501c9f5dfa48abefd9c8b80dd161e5c/chrome/android/java/src/org/chromium/chrome/browser/ChromeTabbedActivity.java
[modify] https://crrev.com/2c81bbb26501c9f5dfa48abefd9c8b80dd161e5c/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellImpl.java
[modify] https://crrev.com/2c81bbb26501c9f5dfa48abefd9c8b80dd161e5c/chrome/browser/android/vr_shell/ui_elements/url_bar.cc
[modify] https://crrev.com/2c81bbb26501c9f5dfa48abefd9c8b80dd161e5c/chrome/browser/android/vr_shell/ui_elements/url_bar.h

Verified in Chrome Canary 61.0.3123.0

 Issue 723833  has been merged into this issue.