Set WebXR Gamepad.id

The following values can be used by JS to determine button mappings of
some common controllers:
"oculus-touch"
"windows-mixed-reality"
"openvr"
"daydream-controller"

Bug: 957740
Change-Id: I231926192578c255114a00fe73efa82f8a088050
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1600599
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Reviewed-by: Tibor Goldschwendt <tiborg@chromium.org>
Reviewed-by: Bill Orr <billorr@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Commit-Queue: Jacob DeWitt <jacde@chromium.org>
Cr-Commit-Position: refs/heads/master@{#657938}
4 files changed