Allow wrapping worker runnables in cancellable runnables.

components/script/dom/bindings/global.rs

@@ -23,7 +23,7 @@ use net_traits::filemanager_thread::FileManagerThreadMsg;
 use net_traits::{ResourceThreads, CoreResourceThread, RequestSource, IpcSend};
 use profile_traits::{mem, time};
 use script_runtime::{CommonScriptMsg, ScriptChan, ScriptPort};
-use script_thread::{MainThreadScriptChan, ScriptThread};
+use script_thread::{MainThreadScriptChan, ScriptThread, RunnableWrapper};
 use script_traits::{MsDuration, ScriptMsg as ConstellationMsg, TimerEventRequest};
 use task_source::dom_manipulation::DOMManipulationTaskSource;
 use timers::{OneshotTimerCallback, OneshotTimerHandle};
@@ -297,6 +297,15 @@ impl<'a> GlobalRef<'a> {
             GlobalRef::Worker(ref worker) => worker.panic_chan(),
         }
     }
+
+    /// Returns a wrapper for runnables to ensure they are cancelled if the global
+    /// is being destroyed.
+    pub fn get_runnable_wrapper(&self) -> RunnableWrapper {
+        match *self {
+            GlobalRef::Window(ref window) => window.get_runnable_wrapper(),
+            GlobalRef::Worker(ref worker) => worker.get_runnable_wrapper(),
+        }
+    }
 }
 
 impl GlobalRoot {

components/script/dom/workerglobalscope.rs

@@ -29,6 +29,7 @@ use net_traits::{LoadContext, ResourceThreads, load_whole_resource};
 use net_traits::{RequestSource, LoadOrigin, CustomResponseSender, IpcSend};
 use profile_traits::{mem, time};
 use script_runtime::{CommonScriptMsg, ScriptChan, ScriptPort, maybe_take_panic_result};
+use script_thread::RunnableWrapper;
 use script_traits::ScriptMsg as ConstellationMsg;
 use script_traits::{MsDuration, TimerEvent, TimerEventId, TimerEventRequest, TimerSource};
 use std::cell::Cell;
@@ -268,6 +269,12 @@ impl WorkerGlobalScope {
     pub fn panic_chan(&self) -> &IpcSender<PanicMsg> {
         &self.panic_chan
     }
+
+    pub fn get_runnable_wrapper(&self) -> RunnableWrapper {
+        RunnableWrapper {
+            cancelled: self.closing.clone(),
+        }
+    }
 }
 
 impl LoadOrigin for WorkerGlobalScope {