The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/907652b824e283a6109261f5e760bf879dc1537a

commit 907652b824e283a6109261f5e760bf879dc1537a
Author: Michael Thiessen <mthiesse@google.com>
Date: Thu Jun 01 15:51:34 2017

VR: Hide 2D screenshot when resuming activities in VR and hide 2D UI while loading VR UI.

This CL adds an animation that keeps the resuming Activity hidden for 500ms while 
starting up to allow time for us to draw the black overlay, also added in this CL,
and prevent 2D UI from being shown while entering VR.

This also performs some cleanup around VR entry (now that it's even more async than
before) to ensure that we don't continue trying to enter VR after we try to exit
VR (like when the activity is paused, etc.).

Bug:  728148 
Change-Id: I344ad661b632bde74764b134e9d9f70f6258d68d
Reviewed-on: https://chromium-review.googlesource.com/519483
Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Yash Malik <ymalik@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/master@{#476301}
[add] https://crrev.com/907652b824e283a6109261f5e760bf879dc1537a/chrome/android/java/res/anim/stay_hidden.xml
[modify] https://crrev.com/907652b824e283a6109261f5e760bf879dc1537a/chrome/android/java/res/values-v17/styles.xml
[modify] https://crrev.com/907652b824e283a6109261f5e760bf879dc1537a/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java

Going to let this bake on Canary for a day or two then request a merge.

 Issue 726590  has been merged into this issue.

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/+/1d2c3e91d531a0565726650dbccceacc39dfb8a7

commit 1d2c3e91d531a0565726650dbccceacc39dfb8a7
Author: Michael Thiessen <mthiesse@google.com>
Date: Mon Jun 05 14:22:46 2017

VR: Hide 2D screenshot when resuming activities in VR and hide 2D UI while loading VR UI.

This CL adds an animation that keeps the resuming Activity hidden for 500ms while
starting up to allow time for us to draw the black overlay, also added in this CL,
and prevent 2D UI from being shown while entering VR.

This also performs some cleanup around VR entry (now that it's even more async than
before) to ensure that we don't continue trying to enter VR after we try to exit
VR (like when the activity is paused, etc.).

Bug:  728148 
Change-Id: I344ad661b632bde74764b134e9d9f70f6258d68d
Reviewed-on: https://chromium-review.googlesource.com/519483
Reviewed-by: David Trainor <dtrainor@chromium.org>
Reviewed-by: Yash Malik <ymalik@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#476301}
Review-Url: https://codereview.chromium.org/2917393002 .
Cr-Commit-Position: refs/branch-heads/3112@{#148}
Cr-Branched-From: b6460e24cf59f429d69de255538d0fc7a425ccf9-refs/heads/master@{#474897}

[add] https://crrev.com/1d2c3e91d531a0565726650dbccceacc39dfb8a7/chrome/android/java/res/anim/stay_hidden.xml
[modify] https://crrev.com/1d2c3e91d531a0565726650dbccceacc39dfb8a7/chrome/android/java/res/values-v17/styles.xml
[modify] https://crrev.com/1d2c3e91d531a0565726650dbccceacc39dfb8a7/chrome/android/java/src/org/chromium/chrome/browser/vr_shell/VrShellDelegate.java

Hi Michael, I verified this in 60.0.3112.78 by checking that after the DON flow, immediately after syncing the controller, and before the 3D presentation starts, no 2D screenshot is displayed. Please let me know if that is not the correct verification. Thanks!