How closely does this issue relate to crbug/655724 ("Fix scheduling so rendering loop is in sync with GVR")?

I ask because I'd like the Javascript UI to manage the WebVr content warnings, and render the quads via the same code path we'd use in 2D VR browsing.  If a lot of rework is needed to fix the jitter, it may impact the JS UI approach.

This is fixed by drawing the warnings in a separate head-locked buffer:

commit 58290e535d3de7a235e13b6f023b1c8bf06a223a
Author: bajones <bajones@chromium.org>
Date:   Fri Oct 21 15:15:32 2016 -0700

    Draw WebVR security overlay with a non-reprojected viewport
    
    This prevents the overlay from jittering regardless of the performance of the
    WebVR content.
    
    BUG= 389343