The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5ef1225bd132d42f2a7be4126fe215fd7ecc447d

commit 5ef1225bd132d42f2a7be4126fe215fd7ecc447d
Author: Michael Thiessen <mthiesse@chromium.org>
Date: Mon Nov 20 21:56:34 2017

VR: pause/resume gvrLayout when Chrome is paused/resumed.

Previously, we would pause/resume the gvrLayout when Chrome is
shown/hidden to avoid tracking stopping before Chrome stops being
visible. However, that issue was fixed in the VR services, so gvr folks
now recommend we actually call pause in onPause.

We still make sure we're actually visible before calling
gvrLayout#onresume so that we don't render frames that won't be seen.

(The gvrLayout is now resumed when we're both visible and resumed, and
paused otherwise)

Bug:  787060 
Change-Id: Ib8e16c140f18a254381d4538dd9d5b271708ba00
Reviewed-on: https://chromium-review.googlesource.com/779250
Reviewed-by: Yash Malik <ymalik@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#517940}
[modify] https://crrev.com/5ef1225bd132d42f2a7be4126fe215fd7ecc447d/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java

mthiesse@ - Is this something in your opinion that could become a manual test case?

Thanks, David

Hmm there's no noticeable difference pre/post patch here, so I don't think you could verify this fix in any way.

One thing that might be worth manual testing is checking that Chrome doesn't appear to freeze (stop tracking head movement) when you hit the home button (to go to DD home).

Great, thanks for the test case!

I'll add the following to our WebVR manual test plan:

(1) Go to https://webvr.info/samples/03-vr-presentation.html and hit Enter VR button.
(2) Insert device in headset and follow DON flow to start WebVR presentation.
(3) Press the Home button on the Daydream controller while moving your head.

Verify that head tracking does not stop before or during the fade to black transition out of WebVR.

Sounds great, thanks David.

Verified in Chrome Dev 64.0.3278.7