This is due to a check in VrShellDelegate when exiting presentation. However, removing that check would cause Cardboard users to be put into the VR browser whenever exiting presentation, which is not the intended behavior.

Since this is technically an unsupported use case anyways, we'll just leave as-is.

Should the VrShellDelegate check also check the flag just as we do when entering the VR browser (not done in this case)? In the Cardboard case, though, it probably makes sense to return to whatever state the user was in when they started. Thus, in this case it probably does make sense to  return to 2D Chrome because that's where the user was before entering the WebVR presentation.

Checking the flag when entering the VR browser would disable the browser entirely on Cardboard, correct? AFAIK there aren't any plans to support the browser in Cardboard, so that might be a good idea so people don't go trying to use an unsupported feature?

Relevant CL and discussion: https://chromium-review.googlesource.com/c/541003/

@#3: I was referring to checks like the following:
1. On request to enter VR browser: if is Daydream OR VR browser chrome flag is enabled, allow.
2. On exitPresent() / back: if is Daydream OR VR browser chrome flag is enabled, enter VR browser.

It's possible that there is no check like #1 - it may be that the only path to entering the VR browser in the non-Daydream case is via UI that is only available when the VR browser chrome flag is enabled. Thus, the condition is enforced by the UX (UI and physical NFC hardware for Daydream).

Just to clarify, there are 2 VR browser flags.  The base one is enabled by default now (turned off in beta for 60) but is not sufficient to allow a cardboard into VR browser (there is no entry point for it).

--vr-shell-dev is the flag that needs to be set for the menu item to show up (which currently allows cardboard access).

If a user has --vr-shell-dev flag set than I think a check on exitPresent to return them to VR Browser would be good (but low priority to add since we don't support the feature and it's not that big a pain to just enter VR again from the menu).

I also think it would be nice to add --vr-shell-dev flag to about://flags so that any user could actually turn it on.  As it is right now, you must have a rooted device to set the command line flag.