Add WebXR samples repo to DEPS

Adds a DEPS entry for the WebXR samples repo to sync to
//chrome/test/data/vr/webxr_samples.

Bug: 837862
Change-Id: I51ba684dbf6c81dc72c2dc1b019136c03d2ae931
Reviewed-on: https://chromium-review.googlesource.com/1034093
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554879}

DEPS

@@ -245,6 +245,9 @@ deps = {
   'src/chrome/test/data/vr/webvr_info':
     Var('chromium_git') + '/external/github.com/toji/webvr.info.git' + '@' + 'c58ae99b9ff9e2aa4c524633519570bf33536248',
 
+  'src/chrome/test/data/vr/webxr_samples':
+    Var('chromium_git') + '/external/github.com/immersive-web/webxr-samples.git' + '@' + '1848aed8fc333030c26787658db8fa4261a2b955',
+
   'src/ios/third_party/earl_grey/src': {
       'url': Var('chromium_git') + '/external/github.com/google/EarlGrey.git' + '@' + '2fd8a7d4b76f820fb95bce495c0ceb324dbe3edb',
       'condition': 'checkout_ios',