Introduce a task! macro and use it for internal pause steps

components/script/dom/htmlmediaelement.rs

@@ -140,15 +140,11 @@ impl HTMLMediaElement {
 
             // Step 2.3.
             let window = window_from_node(self);
+            let target = Trusted::new(self.upcast::<EventTarget>());
             // FIXME(nox): Why are errors silenced here?
             let _ = window.dom_manipulation_task_source().queue(
-                box InternalPauseStepsTask(Trusted::new(self.upcast())),
-                window.upcast(),
-            );
-            struct InternalPauseStepsTask(Trusted<EventTarget>);
-            impl Task for InternalPauseStepsTask {
-                fn run(self: Box<Self>) {
-                    let target = self.0.root();
+                box task!(internal_pause_steps: move || {
+                    let target = target.root();
 
                     // Step 2.3.1.
                     target.fire_event(atom!("timeupdate"));
@@ -159,8 +155,9 @@ impl HTMLMediaElement {
                     // Step 2.3.3.
                     // FIXME(nox): Reject pending play promises with promises
                     // and an "AbortError" DOMException.
-                }
-            }
+                }),
+                window.upcast(),
+            );
 
             // Step 2.4.
             // FIXME(nox): Set the official playback position to the current

components/script/lib.rs

@@ -106,6 +106,9 @@ extern crate webrender_api;
 extern crate webvr_traits;
 extern crate xml5ever;
 
+#[macro_use]
+mod task;
+
 mod body;
 pub mod clipboard_provider;
 mod devtools;
@@ -123,7 +126,6 @@ pub mod script_thread;
 mod serviceworker_manager;
 mod serviceworkerjob;
 mod stylesheet_loader;
-mod task;
 mod task_source;
 pub mod test;
 pub mod textinput;

components/script/task.rs

@@ -9,6 +9,26 @@ use std::intrinsics;
 use std::sync::Arc;
 use std::sync::atomic::{AtomicBool, Ordering};
 
+macro_rules! task {
+    ($name:ident: move || $body:tt) => {{
+        #[allow(non_camel_case_types)]
+        struct $name<F>(F);
+        impl<F> ::task::Task for $name<F>
+        where
+            F: ::std::ops::FnOnce(),
+        {
+            fn name(&self) -> &'static str {
+                stringify!($name)
+            }
+
+            fn run(self: Box<Self>) {
+                (self.0)();
+            }
+        }
+        $name(move || $body)
+    }};
+}
+
 /// A task that can be run. The name method is for profiling purposes.
 pub trait Task {
     #[allow(unsafe_code)]