Added isFirstPersonObserver to XRView, always false

Was added to the WebXR AR Module recently, primarily to enable better
app behavior with AR headsets. Since we don't support any in Chrome
directly we can always return false.

Original WebXR AR Module intent to ship: https://groups.google.com/a/chromium.org/g/blink-dev/c/BXxS2U5EaN0/m/cSVmzxSmDQAJ

Bug: 1101838
Change-Id: I09e53a38b79424b6eb15f894ef1cce3228f316fe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2289055
Commit-Queue: Brandon Jones <bajones@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Cr-Commit-Position: refs/heads/master@{#788292}

third_party/blink/renderer/modules/xr/xr_view.h

@@ -35,6 +35,13 @@ class MODULES_EXPORT XRView final : public ScriptWrappable {
   DOMFloat32Array* projectionMatrix() const;
   XRRigidTransform* transform() const;
 
+  // isFirstPersonObserver is only true for views that composed with a video
+  // feed that is not directly displayed on the viewer device. Primarily this is
+  // used for video streams from optically transparent AR headsets. Since Chrome
+  // does not directly support any such headset at this time we return false
+  // unconditionally.
+  bool isFirstPersonObserver() const { return false; }
+
   void Trace(Visitor*) const override;
 
  private:

third_party/blink/renderer/modules/xr/xr_view.idl

@@ -17,4 +17,8 @@ enum XREye {
   readonly attribute XREye eye;
   readonly attribute Float32Array projectionMatrix;
   [SameObject] readonly attribute XRRigidTransform transform;
+
+  // Added by the AR module.
+  // https://immersive-web.github.io/webxr-ar-module/
+  readonly attribute boolean isFirstPersonObserver;
 };

third_party/blink/web_tests/external/wpt/webxr/ar-module/idlharness.https.window-expected.txt

-This is a testharness.js-based test.
-PASS idl_test setup
-PASS idl_test validation
-PASS Partial interface XRSession: original interface defined
-PASS Partial interface XRSession: member names are unique
-PASS Partial interface XRSession[2]: original interface defined
-PASS Partial interface XRSession[2]: member names are unique
-PASS Partial interface XRView: original interface defined
-PASS Partial interface XRView: member names are unique
-PASS XRSession interface: attribute environmentBlendMode
-PASS XRSession interface: attribute interactionMode
-PASS XRSession interface: xrSession must inherit property "environmentBlendMode" with the proper type
-PASS XRSession interface: xrSession must inherit property "interactionMode" with the proper type
-FAIL XRView interface: attribute isFirstPersonObserver assert_true: The prototype object must have a property "isFirstPersonObserver" expected true got false
-Harness: the test ran to completion.
-

third_party/blink/web_tests/virtual/stable/webexposed/global-interface-listing-expected.txt

@@ -9248,6 +9248,7 @@ interface XRTransientInputHitTestSource
 interface XRView
     attribute @@toStringTag
     getter eye
+    getter isFirstPersonObserver
     getter projectionMatrix
     getter transform
     method constructor

third_party/blink/web_tests/webexposed/global-interface-listing-expected.txt

@@ -11501,6 +11501,7 @@ interface XRTransientInputHitTestSource
 interface XRView
     attribute @@toStringTag
     getter eye
+    getter isFirstPersonObserver
     getter projectionMatrix
     getter transform
     method constructor