Google Chrome 66 came out a few days ago, with your usual list of new APIs and user improvements. However, one major new feature flew under the radar. This is the first stable Chrome release with experimental support for Valve's OpenVR API, allowing VR content to be viewed on all popular headsets. This includes the HTC Vive, Oculus Rift, and Windows Mixed Reality headsets.
The feature currently requires Windows 10, with Steam and SteamVR already installed. Once you update to Chrome 66, go to chrome://flags and enable the #openvr option. Then, visit a page that uses WebVR, like with.in. SteamVR will then open and start displaying content on your headset.
I tried it with my Dell Mixed Reality headset, and it seemed to mostly work, but Chrome occasionally crashed while opening a VR page. Web-based VR content is also rare at the moment, especially since the entire technology is being revamped.