Auto merge of #27513 - asajeffrey:webxr-layer-event, r=Manishearth

Add XRLayerEvent

<!-- Please describe your changes on the following line: -->

Implement the `XRLayerEvent` spec.

---
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- [x] `./mach test-tidy` does not report any errors
- [x] There are tests for these changes

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3 files changed, 68 insertions, 6 deletions

diff --git a/components/script/dom/mod.rs b/components/script/dom/mod.rs
index 76ed789e8ad..a4d27057446 100644
--- a/components/script/dom/mod.rs
+++ b/components/script/dom/mod.rs
@@ -614,6 +614,7 @@ pub mod xrinputsourceschangeevent;
 pub mod xrjointpose;
 pub mod xrjointspace;
 pub mod xrlayer;
+pub mod xrlayerevent;
 pub mod xrmediabinding;
 pub mod xrpose;
 pub mod xrprojectionlayer;
diff --git a/components/script/dom/webidls/XRLayerEvent.webidl b/components/script/dom/webidls/XRLayerEvent.webidl
index c90b9bfb27b..9a05272138e 100644
--- a/components/script/dom/webidls/XRLayerEvent.webidl
+++ b/components/script/dom/webidls/XRLayerEvent.webidl
@@ -3,12 +3,11 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 // https://immersive-web.github.io/layers/#xrlayerevent-interface
-
-// [SecureContext, Exposed=Window]
-// interface XRLayerEvent : Event {
-//   constructor(DOMString type, XRLayerEventInit eventInitDict);
-//   [SameObject] readonly attribute XRLayer layer;
-// };
+[SecureContext, Exposed=Window, Pref="dom.webxr.layers.enabled"]
+interface XRLayerEvent : Event {
+  constructor(DOMString type, XRLayerEventInit eventInitDict);
+  [SameObject] readonly attribute XRLayer layer;
+};
 
 dictionary XRLayerEventInit : EventInit {
   required XRLayer layer;
diff --git a/components/script/dom/xrlayerevent.rs b/components/script/dom/xrlayerevent.rs
new file mode 100644
index 00000000000..d3485fa1c51
--- /dev/null
+++ b/components/script/dom/xrlayerevent.rs
@@ -0,0 +1,62 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use crate::dom::bindings::codegen::Bindings::EventBinding::EventBinding::EventMethods;
+use crate::dom::bindings::codegen::Bindings::XRLayerEventBinding::XRLayerEventInit;
+use crate::dom::bindings::codegen::Bindings::XRLayerEventBinding::XRLayerEventMethods;
+use crate::dom::bindings::reflector::reflect_dom_object;
+use crate::dom::bindings::root::Dom;
+use crate::dom::bindings::root::DomRoot;
+use crate::dom::bindings::str::DOMString;
+use crate::dom::event::Event;
+use crate::dom::window::Window;
+use crate::dom::xrlayer::XRLayer;
+use dom_struct::dom_struct;
+use servo_atoms::Atom;
+
+// https://w3c.github.io/uievents/#interface-uievent
+#[dom_struct]
+pub struct XRLayerEvent {
+    event: Event,
+    layer: Dom<XRLayer>,
+}
+
+impl XRLayerEvent {
+    pub fn new_inherited(layer: &XRLayer) -> XRLayerEvent {
+        XRLayerEvent {
+            event: Event::new_inherited(),
+            layer: Dom::from_ref(layer),
+        }
+    }
+
+    pub fn new(window: &Window, layer: &XRLayer) -> DomRoot<XRLayerEvent> {
+        reflect_dom_object(Box::new(XRLayerEvent::new_inherited(layer)), window)
+    }
+
+    #[allow(non_snake_case)]
+    pub fn Constructor(
+        window: &Window,
+        type_: DOMString,
+        init: &XRLayerEventInit,
+    ) -> DomRoot<XRLayerEvent> {
+        let event = XRLayerEvent::new(window, &init.layer);
+        let type_ = Atom::from(type_);
+        let bubbles = init.parent.bubbles;
+        let cancelable = init.parent.cancelable;
+        event.event.init_event(type_, bubbles, cancelable);
+        event
+    }
+}
+
+impl XRLayerEventMethods for XRLayerEvent {
+    // https://immersive-web.github.io/layers/#dom-xrlayerevent-layer
+    fn Layer(&self) -> DomRoot<XRLayer> {
+        DomRoot::from_ref(&self.layer)
+    }
+
+    // https://dom.spec.whatwg.org/#dom-event-istrusted
+    fn IsTrusted(&self) -> bool {
+        self.event.IsTrusted()
+    }
+}