PerformanceObserver.supportedEntryTypes

components/script/dom/extendablemessageevent.rs

@@ -159,10 +159,13 @@ impl ExtendableMessageEventMethods for ExtendableMessageEvent {
             .collect();
         let frozen_ports = to_frozen_array(ports.as_slice(), cx);
 
-        // Cache the Js value.
-        let heap_val = Heap::default();
-        heap_val.set(frozen_ports);
-        *self.frozen_ports.borrow_mut() = Some(heap_val);
+        // Safety: need to create the Heap value in its final memory location before setting it.
+        *self.frozen_ports.borrow_mut() = Some(Heap::default());
+        self.frozen_ports
+            .borrow()
+            .as_ref()
+            .unwrap()
+            .set(frozen_ports);
 
         frozen_ports
     }

components/script/dom/globalscope.rs

@@ -16,6 +16,7 @@ use crate::dom::bindings::root::{DomRoot, MutNullableDom};
 use crate::dom::bindings::settings_stack::{entry_global, incumbent_global, AutoEntryScript};
 use crate::dom::bindings::str::DOMString;
 use crate::dom::bindings::structuredclone;
+use crate::dom::bindings::utils::to_frozen_array;
 use crate::dom::bindings::weakref::{DOMTracker, WeakRef};
 use crate::dom::blob::Blob;
 use crate::dom::crypto::Crypto;
@@ -31,6 +32,7 @@ use crate::dom::messageevent::MessageEvent;
 use crate::dom::messageport::MessagePort;
 use crate::dom::paintworkletglobalscope::PaintWorkletGlobalScope;
 use crate::dom::performance::Performance;
+use crate::dom::performanceobserver::VALID_ENTRY_TYPES;
 use crate::dom::promise::Promise;
 use crate::dom::window::Window;
 use crate::dom::workerglobalscope::WorkerGlobalScope;
@@ -63,7 +65,7 @@ use js::jsapi::JSObject;
 use js::jsapi::{CurrentGlobalOrNull, GetNonCCWObjectGlobal};
 use js::jsapi::{HandleObject, Heap};
 use js::jsapi::{JSAutoRealm, JSContext};
-use js::jsval::UndefinedValue;
+use js::jsval::{JSVal, UndefinedValue};
 use js::panic::maybe_resume_unwind;
 use js::rust::wrappers::EvaluateUtf8;
 use js::rust::{get_object_class, CompileOptionsWrapper, ParentRuntime, Runtime};
@@ -222,6 +224,10 @@ pub struct GlobalScope {
 
     #[ignore_malloc_size_of = "defined in wgpu"]
     gpu_id_hub: RefCell<Identities>,
+
+    // https://w3c.github.io/performance-timeline/#supportedentrytypes-attribute
+    #[ignore_malloc_size_of = "mozjs"]
+    frozen_supported_performance_entry_types: DomRefCell<Option<Heap<JSVal>>>,
 }
 
 /// A wrapper for glue-code between the ipc router and the event-loop.
@@ -513,6 +519,7 @@ impl GlobalScope {
             is_headless,
             user_agent,
             gpu_id_hub: RefCell::new(Identities::new()),
+            frozen_supported_performance_entry_types: DomRefCell::new(Default::default()),
         }
     }
 
@@ -2087,6 +2094,29 @@ impl GlobalScope {
         unreachable!();
     }
 
+    // https://w3c.github.io/performance-timeline/#supportedentrytypes-attribute
+    pub fn supported_performance_entry_types(&self, cx: SafeJSContext) -> JSVal {
+        if let Some(types) = &*self.frozen_supported_performance_entry_types.borrow() {
+            return types.get();
+        }
+
+        let types: Vec<DOMString> = VALID_ENTRY_TYPES
+            .iter()
+            .map(|t| DOMString::from(t.to_string()))
+            .collect();
+        let frozen_types = to_frozen_array(types.as_slice(), cx);
+
+        // Safety: need to create the Heap value in its final memory location before setting it.
+        *self.frozen_supported_performance_entry_types.borrow_mut() = Some(Heap::default());
+        self.frozen_supported_performance_entry_types
+            .borrow()
+            .as_ref()
+            .unwrap()
+            .set(frozen_types);
+
+        frozen_types
+    }
+
     pub fn is_headless(&self) -> bool {
         self.is_headless
     }

components/script/dom/messageevent.rs

@@ -255,10 +255,13 @@ impl MessageEventMethods for MessageEvent {
             .collect();
         let frozen_ports = to_frozen_array(ports.as_slice(), cx);
 
-        // Cache the Js value.
-        let heap_val = Heap::default();
-        heap_val.set(frozen_ports);
-        *self.frozen_ports.borrow_mut() = Some(heap_val);
+        // Safety: need to create the Heap value in its final memory location before setting it.
+        *self.frozen_ports.borrow_mut() = Some(Heap::default());
+        self.frozen_ports
+            .borrow()
+            .as_ref()
+            .unwrap()
+            .set(frozen_ports);
 
         frozen_ports
     }

components/script/dom/performanceobserver.rs

@@ -18,19 +18,21 @@ use crate::dom::globalscope::GlobalScope;
 use crate::dom::performance::PerformanceEntryList;
 use crate::dom::performanceentry::PerformanceEntry;
 use crate::dom::performanceobserverentrylist::PerformanceObserverEntryList;
+use crate::script_runtime::JSContext;
 use dom_struct::dom_struct;
+use js::jsval::JSVal;
 use std::cell::Cell;
 use std::rc::Rc;
 
-/// List of allowed performance entry types.
-const VALID_ENTRY_TYPES: &'static [&'static str] = &[
+/// List of allowed performance entry types, in alphabetical order.
+pub const VALID_ENTRY_TYPES: &'static [&'static str] = &[
+    // "frame", //TODO Frame Timing API
     "mark",       // User Timing API
     "measure",    // User Timing API
-    "resource",   // Resource Timing API
     "navigation", // Navigation Timing API
-    // "frame", //TODO Frame Timing API
-    // "server", XXX Server Timing API
-    "paint", // Paint Timing API
+    "paint",      // Paint Timing API
+    "resource",   // Resource Timing API
+                  // "server", XXX Server Timing API
 ];
 
 #[derive(Clone, Copy, JSTraceable, MallocSizeOf, PartialEq)]
@@ -110,6 +112,14 @@ impl PerformanceObserver {
     pub fn set_entries(&self, entries: DOMPerformanceEntryList) {
         *self.entries.borrow_mut() = entries;
     }
+
+    // https://w3c.github.io/performance-timeline/#supportedentrytypes-attribute
+    #[allow(non_snake_case)]
+    pub fn SupportedEntryTypes(cx: JSContext, global: &GlobalScope) -> JSVal {
+        // While this is exposed through a method of PerformanceObserver,
+        // it is specified as associated with the global scope.
+        global.supported_performance_entry_types(cx)
+    }
 }
 
 impl PerformanceObserverMethods for PerformanceObserver {

components/script/dom/webidls/PerformanceObserver.webidl

@@ -21,5 +21,6 @@ interface PerformanceObserver {
   void observe(optional PerformanceObserverInit options = {});
   void disconnect();
   PerformanceEntryList takeRecords();
-  // [SameObject] static readonly attribute FrozenArray<DOMString> supportedEntryTypes;
+  // codegen doesn't like SameObject+static and doesn't know FrozenArray
+  /*[SameObject]*/ static readonly attribute /*FrozenArray<DOMString>*/ any supportedEntryTypes;
 };

tests/wpt/metadata/navigation-timing/supported_navigation_type.window.js.ini

@@ -1,4 +1,4 @@
 [supported_navigation_type.window.html]
-  [supportedEntryTypes contains 'navigation'.]
-    expected: FAIL
-
+  expected: TIMEOUT
+  ['navigation' entries should be observable.]
+    expected: TIMEOUT

tests/wpt/metadata/performance-timeline/idlharness.any.js.ini

@@ -11,9 +11,6 @@
   [Test default toJSON operation of PerformanceMark]
     expected: FAIL
 
-  [PerformanceObserver interface: attribute supportedEntryTypes]
-    expected: FAIL
-
   [PerformanceMark interface: attribute detail]
     expected: FAIL
 
@@ -31,9 +28,6 @@
   [Test default toJSON operation of PerformanceMark]
     expected: FAIL
 
-  [PerformanceObserver interface: attribute supportedEntryTypes]
-    expected: FAIL
-
   [PerformanceMark interface: attribute detail]
     expected: FAIL