2 files changed, 15 insertions, 1 deletions
diff --git a/components/script/dom/webidls/XRSession.webidl b/components/script/dom/webidls/XRSession.webidl
index 1548a68730d..507579225ab 100644
--- a/components/script/dom/webidls/XRSession.webidl
+++ b/components/script/dom/webidls/XRSession.webidl
@@ -10,6 +10,12 @@ enum XREnvironmentBlendMode {
   "alpha-blend",
 };
 
+enum XRVisibilityState {
+  "visible",
+  "visible-blurred",
+  "hidden",
+};
+
 callback XRFrameRequestCallback = void (DOMHighResTimeStamp time, XRFrame frame);
 
 [SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
@@ -17,7 +23,7 @@ interface XRSession : EventTarget {
   // // Attributes
   readonly attribute XREnvironmentBlendMode environmentBlendMode;
 
-  // readonly attribute XRVisibilityState visibilityState;
+  readonly attribute XRVisibilityState visibilityState;
   [SameObject] readonly attribute XRRenderState renderState;
   [SameObject] readonly attribute XRInputSourceArray inputSources;
 
diff --git a/components/script/dom/xrsession.rs b/components/script/dom/xrsession.rs
index 1e63bdb2eaa..906b7c0cbe5 100644
--- a/components/script/dom/xrsession.rs
+++ b/components/script/dom/xrsession.rs
@@ -16,6 +16,7 @@ use crate::dom::bindings::codegen::Bindings::XRSessionBinding;
 use crate::dom::bindings::codegen::Bindings::XRSessionBinding::XREnvironmentBlendMode;
 use crate::dom::bindings::codegen::Bindings::XRSessionBinding::XRFrameRequestCallback;
 use crate::dom::bindings::codegen::Bindings::XRSessionBinding::XRSessionMethods;
+use crate::dom::bindings::codegen::Bindings::XRSessionBinding::XRVisibilityState;
 use crate::dom::bindings::codegen::Bindings::XRWebGLLayerBinding::XRWebGLLayerMethods;
 use crate::dom::bindings::error::{Error, ErrorResult};
 use crate::dom::bindings::inheritance::Castable;
@@ -55,6 +56,7 @@ pub struct XRSession {
     eventtarget: EventTarget,
     base_layer: MutNullableDom<XRWebGLLayer>,
     blend_mode: XREnvironmentBlendMode,
+    visibility_state: Cell<XRVisibilityState>,
     viewer_space: MutNullableDom<XRSpace>,
     #[ignore_malloc_size_of = "defined in webxr"]
     session: DomRefCell<Session>,
@@ -85,6 +87,7 @@ impl XRSession {
             eventtarget: EventTarget::new_inherited(),
             base_layer: Default::default(),
             blend_mode: session.environment_blend_mode().into(),
+            visibility_state: Cell::new(XRVisibilityState::Visible),
             viewer_space: Default::default(),
             session: DomRefCell::new(session),
             frame_requested: Cell::new(false),
@@ -405,6 +408,11 @@ impl XRSessionMethods for XRSession {
         self.blend_mode
     }
 
+    /// https://immersive-web.github.io/webxr/#dom-xrsession-visibilitystate
+    fn VisibilityState(&self) -> XRVisibilityState {
+        self.visibility_state.get()
+    }
+
     /// https://immersive-web.github.io/webxr/#dom-xrsession-requestreferencespace
     fn RequestReferenceSpace(&self, ty: XRReferenceSpaceType, comp: InCompartment) -> Rc<Promise> {
         let p = Promise::new_in_current_compartment(&self.global(), comp);