The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/45c6392a896fefd5bdaef09d80920a55e1ea2ac4

commit 45c6392a896fefd5bdaef09d80920a55e1ea2ac4
Author: mthiesse <mthiesse@chromium.org>
Date: Fri Feb 24 01:45:24 2017

Prevent browser crash resulting from misbehaving WebVR renderer requesting multiple VSyncs.

This also fixes a logic error, where if we have multiple rAF loops running for the same VrDisplay, we mistakenly fire off a VSync request for each rAF loop, when we should be sending only one at a time.

BUG= 695470 

Review-Url: https://codereview.chromium.org/2711173002
Cr-Commit-Position: refs/heads/master@{#452711}

[modify] https://crrev.com/45c6392a896fefd5bdaef09d80920a55e1ea2ac4/chrome/browser/android/vr_shell/non_presenting_gvr_delegate.cc
[modify] https://crrev.com/45c6392a896fefd5bdaef09d80920a55e1ea2ac4/chrome/browser/android/vr_shell/vr_shell_gl.cc
[modify] https://crrev.com/45c6392a896fefd5bdaef09d80920a55e1ea2ac4/device/vr/vr_service.mojom
[modify] https://crrev.com/45c6392a896fefd5bdaef09d80920a55e1ea2ac4/third_party/WebKit/LayoutTests/vr/resources/mock-vr-service.js
[modify] https://crrev.com/45c6392a896fefd5bdaef09d80920a55e1ea2ac4/third_party/WebKit/Source/modules/vr/VRDisplay.cpp
[modify] https://crrev.com/45c6392a896fefd5bdaef09d80920a55e1ea2ac4/third_party/WebKit/Source/modules/vr/VRDisplay.h