A couple of devices these days support HDR, though not many apps do. YouTube, Netflix, and Google Play Movies are among those apps that can handle HDR playback, and one more may soon be joining them: Chrome. This information comes courtesy of two commits that were recently spotted on Chromium Gerrit.
These first commit demonstrates that Chrome for Android will be able to "tak[e] the VP9 HDR metadata from the video container and [pass] it to MediaCodec." The second says it'll be able to "set color space and HDR metadata in android.media.MediaFormat," or in plain English, played back if the device supports it.
Hopefully we see more HDR content start popping up, as the capability to play it is virtually useless if the content doesn't exist itself. While 4K did take a while to catch on, there's a decent amount of 4K stuff nowadays.