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diff --git a/components/script/dom/bindings/global.rs b/components/script/dom/bindings/global.rs
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+++ b/components/script/dom/bindings/global.rs
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+/* 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 http://mozilla.org/MPL/2.0/. */
+
+//! Abstractions for global scopes.
+//!
+//! This module contains smart pointers to global scopes, to simplify writing
+//! code that works in workers as well as window scopes.
+
+use dom::bindings::js::{JS, JSRef, Root};
+use dom::bindings::utils::{Reflectable, Reflector};
+use dom::workerglobalscope::WorkerGlobalScope;
+use dom::window::Window;
+use script_task::ScriptChan;
+
+use servo_net::resource_task::ResourceTask;
+
+use js::jsapi::JSContext;
+
+use url::Url;
+
+/// A freely-copyable reference to a rooted global object.
+pub enum GlobalRef<'a> {
+    Window(JSRef<'a, Window>),
+    Worker(JSRef<'a, WorkerGlobalScope>),
+}
+
+/// A stack-based rooted reference to a global object.
+pub enum GlobalRoot<'a, 'b> {
+    WindowRoot(Root<'a, 'b, Window>),
+    WorkerRoot(Root<'a, 'b, WorkerGlobalScope>),
+}
+
+/// A traced reference to a global object, for use in fields of traced Rust
+/// structures.
+#[deriving(Encodable)]
+pub enum GlobalField {
+    WindowField(JS<Window>),
+    WorkerField(JS<WorkerGlobalScope>),
+}
+
+impl<'a> GlobalRef<'a> {
+    /// Get the `JSContext` for the `JSRuntime` associated with the thread
+    /// this global object is on.
+    pub fn get_cx(&self) -> *mut JSContext {
+        match *self {
+            Window(ref window) => window.get_cx(),
+            Worker(ref worker) => worker.get_cx(),
+        }
+    }
+
+    /// Extract a `Window`, causing task failure if the global object is not
+    /// a `Window`.
+    pub fn as_window<'b>(&'b self) -> &'b JSRef<'b, Window> {
+        match *self {
+            Window(ref window) => window,
+            Worker(_) => fail!("expected a Window scope"),
+        }
+    }
+
+    pub fn resource_task(&self) -> ResourceTask {
+        match *self {
+            Window(ref window) => window.page().resource_task.deref().clone(),
+            Worker(ref worker) => worker.resource_task().clone(),
+        }
+    }
+
+    pub fn get_url(&self) -> Url {
+        match *self {
+            Window(ref window) => window.get_url(),
+            Worker(ref worker) => worker.get_url().clone(),
+        }
+    }
+
+    /// `ScriptChan` used to send messages to the event loop of this global's
+    /// thread.
+    pub fn script_chan<'b>(&'b self) -> &'b ScriptChan {
+        match *self {
+            Window(ref window) => &window.script_chan,
+            Worker(ref worker) => worker.script_chan(),
+        }
+    }
+}
+
+impl<'a> Reflectable for GlobalRef<'a> {
+    fn reflector<'b>(&'b self) -> &'b Reflector {
+        match *self {
+            Window(ref window) => window.reflector(),
+            Worker(ref worker) => worker.reflector(),
+        }
+    }
+}
+
+impl<'a, 'b> GlobalRoot<'a, 'b> {
+    /// Obtain a safe reference to the global object that cannot outlive the
+    /// lifetime of this root.
+    pub fn root_ref<'c>(&'c self) -> GlobalRef<'c> {
+        match *self {
+            WindowRoot(ref window) => Window(window.root_ref()),
+            WorkerRoot(ref worker) => Worker(worker.root_ref()),
+        }
+    }
+}
+
+impl GlobalField {
+    /// Create a new `GlobalField` from a rooted reference.
+    pub fn from_rooted(global: &GlobalRef) -> GlobalField {
+        match *global {
+            Window(ref window) => WindowField(JS::from_rooted(window)),
+            Worker(ref worker) => WorkerField(JS::from_rooted(worker)),
+        }
+    }
+
+    /// Create a stack-bounded root for this reference.
+    pub fn root(&self) -> GlobalRoot {
+        match *self {
+            WindowField(ref window) => WindowRoot(window.root()),
+            WorkerField(ref worker) => WorkerRoot(worker.root()),
+        }
+    }
+}