Bug 1596891 [wpt PR 20278] - Remove size_x and size_z from VRStageParameters, a=testonly

Automatic update from web-platform-tests
Remove size_x and size_z from VRStageParameters

The notion of a simple "size" for Stage Parameters/bounded was a WebVr
concept that did not carry over to WebXr.  To simplify the mojom, move
the "conversion" of square stages (for those runtimes that only support
giving size x/z) down into a utility function in the device process.

Bug: 1017843
Change-Id: Ib050a7ea3655a3816f6008e82434435ecb2c4426
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1918037
Commit-Queue: Alexander Cooper <alcooper@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Brandon Jones <bajones@chromium.org>
Reviewed-by: Klaus Weidner <klausw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718364}

--

wpt-commits: 0c3a6b1df6317496373d9ce3044d19704e9a6379
wpt-pr: 20278

testing/web-platform/tests/resources/chromium/webxr-test.js

@@ -11,8 +11,6 @@ default_standing.matrix = [1, 0, 0, 0,
                            0, 1.65, 0, 1];
 const default_stage_parameters = {
   standingTransform: default_standing,
-  sizeX: 0,
-  sizeZ: 0,
   bounds: null
 };