Chrome Version: 69.0.3495.0
OS: O
Device: Lenovo VR AIO device

What steps will reproduce the problem? (requires enabling WebXR flags)
(1) Go to https://immersive-web.github.io/webxr-samples/
(2) Scroll down and select "360 Stereo Photos" link
(3) Click on Enter VR button
(4) Once presentation successfully starts, press controller app button to exit back to VR Browsing.

What is the expected result? Page doesn't crash

What happens instead? Page crashes. Repros ~1/3 times.

Crash ID's:

Crashes (2) Uploaded Crash Report ID 6e43083d29c3d986 (Local Crash ID: Chrome) Crash report uploaded on Monday, July 23, 2018 at 7:54:06 AM 

Uploaded Crash Report ID 2b60dedfb099a8d4 (Local Crash ID: Chrome) Crash report uploaded on Monday, July 23, 2018 at 7:53:13 AM