https://crrev.com/c/1046107 adds RequestSession() to VRDisplayHost but only calls it for WebXR. The comment says it must be called before other methods, but it is not called from WebVR.
To satisfy the requirement, we should at least call it before the VRDisplay is used for anything. This also makes sense because a VRDisplay essentially always has a non-exclusive session.
To satisfy the requirement, we should at least call it from VRController::OnDisplayConnected(), which will ensure it is called before the application has an opportunity to cause those other methods to be called. This also makes sense because a VRDisplay essentially always has a non-exclusive session.
When RequestSession() is updated to take information about the session type being requested, we will also need to call it from requestPresent().
Comment 1 by ddorwin@chromium.org
, May 26 2018