Auto merge of #11270 - servo:ConstellationChan, r=asajeffrey

Remove ConstellationChan.

Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data:
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy --faster` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

Either:
- [ ] There are tests for these changes OR
- [x] These changes do not require tests because _____

Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process.

It's a pointless abstraction that propagates the obsolete chan terminology,
swaps the order in which the sender and receiver are returned, and hides a
source of panics.

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15 files changed, 61 insertions, 95 deletions

diff --git a/components/script/clipboard_provider.rs b/components/script/clipboard_provider.rs
index c11944f1697..e8a9552277a 100644
--- a/components/script/clipboard_provider.rs
+++ b/components/script/clipboard_provider.rs
@@ -2,8 +2,7 @@
  * 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/. */
 
-use ipc_channel::ipc;
-use msg::constellation_msg::ConstellationChan;
+use ipc_channel::ipc::{self, IpcSender};
 use script_traits::ScriptMsg as ConstellationMsg;
 use std::borrow::ToOwned;
 
@@ -14,14 +13,14 @@ pub trait ClipboardProvider {
     fn set_clipboard_contents(&mut self, String);
 }
 
-impl ClipboardProvider for ConstellationChan<ConstellationMsg> {
+impl ClipboardProvider for IpcSender<ConstellationMsg> {
     fn clipboard_contents(&mut self) -> String {
         let (tx, rx) = ipc::channel().unwrap();
-        self.0.send(ConstellationMsg::GetClipboardContents(tx)).unwrap();
+        self.send(ConstellationMsg::GetClipboardContents(tx)).unwrap();
         rx.recv().unwrap()
     }
     fn set_clipboard_contents(&mut self, s: String) {
-        self.0.send(ConstellationMsg::SetClipboardContents(s)).unwrap();
+        self.send(ConstellationMsg::SetClipboardContents(s)).unwrap();
     }
 }
 
diff --git a/components/script/dom/bindings/global.rs b/components/script/dom/bindings/global.rs
index d9c5b8d64cb..b48a941af01 100644
--- a/components/script/dom/bindings/global.rs
+++ b/components/script/dom/bindings/global.rs
@@ -18,7 +18,7 @@ use ipc_channel::ipc::IpcSender;
 use js::jsapi::{CurrentGlobalOrNull, GetGlobalForObjectCrossCompartment};
 use js::jsapi::{JSContext, JSObject, JS_GetClass, MutableHandleValue};
 use js::{JSCLASS_IS_DOMJSCLASS, JSCLASS_IS_GLOBAL};
-use msg::constellation_msg::{ConstellationChan, PanicMsg, PipelineId};
+use msg::constellation_msg::{PanicMsg, PipelineId};
 use net_traits::ResourceThread;
 use profile_traits::{mem, time};
 use script_runtime::{CommonScriptMsg, ScriptChan, ScriptPort};
@@ -89,8 +89,8 @@ impl<'a> GlobalRef<'a> {
         }
     }
 
-    /// Get a `ConstellationChan` to send messages to the constellation channel when available.
-    pub fn constellation_chan(&self) -> &ConstellationChan<ConstellationMsg> {
+    /// Get a `IpcSender` to send messages to the constellation when available.
+    pub fn constellation_chan(&self) -> &IpcSender<ConstellationMsg> {
         match *self {
             GlobalRef::Window(window) => window.constellation_chan(),
             GlobalRef::Worker(worker) => worker.constellation_chan(),
diff --git a/components/script/dom/bindings/trace.rs b/components/script/dom/bindings/trace.rs
index 7e6d16f59db..1acb5ee9e4b 100644
--- a/components/script/dom/bindings/trace.rs
+++ b/components/script/dom/bindings/trace.rs
@@ -55,7 +55,6 @@ use js::jsval::JSVal;
 use js::rust::Runtime;
 use layout_interface::{LayoutChan, LayoutRPC};
 use libc;
-use msg::constellation_msg::ConstellationChan;
 use msg::constellation_msg::{PipelineId, SubpageId, WindowSizeData, WindowSizeType, ReferrerPolicy};
 use net_traits::image::base::{Image, ImageMetadata};
 use net_traits::image_cache_thread::{ImageCacheChan, ImageCacheThread};
@@ -66,7 +65,7 @@ use offscreen_gl_context::GLLimits;
 use profile_traits::mem::ProfilerChan as MemProfilerChan;
 use profile_traits::time::ProfilerChan as TimeProfilerChan;
 use script_runtime::ScriptChan;
-use script_traits::{LayoutMsg, ScriptMsg, TimerEventId, TimerSource, TouchpadPressurePhase, UntrustedNodeAddress};
+use script_traits::{TimerEventId, TimerSource, TouchpadPressurePhase, UntrustedNodeAddress};
 use serde::{Deserialize, Serialize};
 use smallvec::SmallVec;
 use std::boxed::FnBox;
@@ -323,20 +322,6 @@ no_jsmanaged_fields!(SharedRt);
 no_jsmanaged_fields!(TouchpadPressurePhase);
 no_jsmanaged_fields!(ReferrerPolicy);
 
-impl JSTraceable for ConstellationChan<ScriptMsg> {
-    #[inline]
-    fn trace(&self, _trc: *mut JSTracer) {
-        // Do nothing
-    }
-}
-
-impl JSTraceable for ConstellationChan<LayoutMsg> {
-    #[inline]
-    fn trace(&self, _trc: *mut JSTracer) {
-        // Do nothing
-    }
-}
-
 impl JSTraceable for Box<ScriptChan + Send> {
     #[inline]
     fn trace(&self, _trc: *mut JSTracer) {
diff --git a/components/script/dom/canvasrenderingcontext2d.rs b/components/script/dom/canvasrenderingcontext2d.rs
index ac7215d3293..e7ac0813174 100644
--- a/components/script/dom/canvasrenderingcontext2d.rs
+++ b/components/script/dom/canvasrenderingcontext2d.rs
@@ -123,7 +123,7 @@ impl CanvasRenderingContext2D {
                      -> CanvasRenderingContext2D {
         let (sender, receiver) = ipc::channel().unwrap();
         let constellation_chan = global.constellation_chan();
-        constellation_chan.0.send(ConstellationMsg::CreateCanvasPaintThread(size, sender)).unwrap();
+        constellation_chan.send(ConstellationMsg::CreateCanvasPaintThread(size, sender)).unwrap();
         let ipc_renderer = receiver.recv().unwrap();
         CanvasRenderingContext2D {
             reflector_: Reflector::new(),
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 866b698687d..f6000e28a8b 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -94,7 +94,7 @@ use js::jsapi::JS_GetRuntime;
 use js::jsapi::{JSContext, JSObject, JSRuntime};
 use layout_interface::{LayoutChan, Msg, ReflowQueryType};
 use msg::constellation_msg::{ALT, CONTROL, SHIFT, SUPER};
-use msg::constellation_msg::{ConstellationChan, Key, KeyModifiers, KeyState};
+use msg::constellation_msg::{Key, KeyModifiers, KeyState};
 use msg::constellation_msg::{PipelineId, ReferrerPolicy, SubpageId};
 use net_traits::ControlMsg::{GetCookiesForUrl, SetCookiesForUrl};
 use net_traits::CookieSource::NonHTTP;
@@ -623,9 +623,8 @@ impl Document {
             // Update the focus state for all elements in the focus chain.
             // https://html.spec.whatwg.org/multipage/#focus-chain
             if focus_type == FocusType::Element {
-                let ConstellationChan(ref chan) = *self.window.constellation_chan();
                 let event = ConstellationMsg::Focus(self.window.pipeline());
-                chan.send(event).unwrap();
+                self.window.constellation_chan().send(event).unwrap();
             }
         }
     }
@@ -699,7 +698,7 @@ impl Document {
                 let event = ConstellationMsg::ForwardMouseButtonEvent(pipeline_id,
                                                                       mouse_event_type,
                                                                       button, child_point);
-                self.window.constellation_chan().0.send(event).unwrap();
+                self.window.constellation_chan().send(event).unwrap();
             }
             return;
         }
@@ -880,7 +879,7 @@ impl Document {
                     let child_point = client_point - child_origin;
 
                     let event = ConstellationMsg::ForwardMouseMoveEvent(pipeline_id, child_point);
-                    self.window.constellation_chan().0.send(event).unwrap();
+                    self.window.constellation_chan().send(event).unwrap();
                 }
                 return;
             }
@@ -1270,11 +1269,10 @@ impl Document {
     pub fn trigger_mozbrowser_event(&self, event: MozBrowserEvent) {
         if htmliframeelement::mozbrowser_enabled() {
             if let Some((containing_pipeline_id, subpage_id)) = self.window.parent_info() {
-                let ConstellationChan(ref chan) = *self.window.constellation_chan();
                 let event = ConstellationMsg::MozBrowserEvent(containing_pipeline_id,
                                                               subpage_id,
                                                               event);
-                chan.send(event).unwrap();
+                self.window.constellation_chan().send(event).unwrap();
             }
         }
     }
@@ -1294,11 +1292,10 @@ impl Document {
         //
         // TODO: Should tick animation only when document is visible
         if !self.running_animation_callbacks.get() {
-            let ConstellationChan(ref chan) = *self.window.constellation_chan();
             let event = ConstellationMsg::ChangeRunningAnimationsState(
                 self.window.pipeline(),
                 AnimationState::AnimationCallbacksPresent);
-            chan.send(event).unwrap();
+            self.window.constellation_chan().send(event).unwrap();
         }
 
         ident
@@ -1308,10 +1305,9 @@ impl Document {
     pub fn cancel_animation_frame(&self, ident: u32) {
         self.animation_frame_list.borrow_mut().remove(&ident);
         if self.animation_frame_list.borrow().is_empty() {
-            let ConstellationChan(ref chan) = *self.window.constellation_chan();
             let event = ConstellationMsg::ChangeRunningAnimationsState(self.window.pipeline(),
                                                                        AnimationState::NoAnimationCallbacksPresent);
-            chan.send(event).unwrap();
+            self.window.constellation_chan().send(event).unwrap();
         }
     }
 
@@ -1333,10 +1329,9 @@ impl Document {
         // the next frame (which is the common case), we won't send a NoAnimationCallbacksPresent
         // message quickly followed by an AnimationCallbacksPresent message.
         if self.animation_frame_list.borrow().is_empty() {
-            let ConstellationChan(ref chan) = *self.window.constellation_chan();
             let event = ConstellationMsg::ChangeRunningAnimationsState(self.window.pipeline(),
                                                                        AnimationState::NoAnimationCallbacksPresent);
-            chan.send(event).unwrap();
+            self.window.constellation_chan().send(event).unwrap();
         }
 
         self.running_animation_callbacks.set(false);
@@ -1495,9 +1490,8 @@ impl Document {
 
     pub fn notify_constellation_load(&self) {
         let pipeline_id = self.window.pipeline();
-        let ConstellationChan(ref chan) = *self.window.constellation_chan();
         let event = ConstellationMsg::DOMLoad(pipeline_id);
-        chan.send(event).unwrap();
+        self.window.constellation_chan().send(event).unwrap();
 
     }
 
diff --git a/components/script/dom/htmlbodyelement.rs b/components/script/dom/htmlbodyelement.rs
index 5b4b9a48cb6..2fd18a00c08 100644
--- a/components/script/dom/htmlbodyelement.rs
+++ b/components/script/dom/htmlbodyelement.rs
@@ -15,7 +15,6 @@ use dom::eventtarget::EventTarget;
 use dom::htmlelement::HTMLElement;
 use dom::node::{Node, document_from_node, window_from_node};
 use dom::virtualmethods::VirtualMethods;
-use msg::constellation_msg::ConstellationChan;
 use script_traits::ScriptMsg as ConstellationMsg;
 use std::rc::Rc;
 use string_cache::Atom;
@@ -153,9 +152,8 @@ impl VirtualMethods for HTMLBodyElement {
         let window = window_from_node(self);
         let document = window.Document();
         document.set_reflow_timeout(time::precise_time_ns() + INITIAL_REFLOW_DELAY);
-        let ConstellationChan(ref chan) = *window.constellation_chan();
         let event = ConstellationMsg::HeadParsed;
-        chan.send(event).unwrap();
+        window.constellation_chan().send(event).unwrap();
     }
 
     fn parse_plain_attribute(&self, name: &Atom, value: DOMString) -> AttrValue {
diff --git a/components/script/dom/htmliframeelement.rs b/components/script/dom/htmliframeelement.rs
index d31c8a09484..db7728ca710 100644
--- a/components/script/dom/htmliframeelement.rs
+++ b/components/script/dom/htmliframeelement.rs
@@ -33,8 +33,7 @@ use ipc_channel::ipc;
 use js::jsapi::{JSAutoCompartment, RootedValue, JSContext, MutableHandleValue};
 use js::jsval::{UndefinedValue, NullValue};
 use layout_interface::ReflowQueryType;
-use msg::constellation_msg::{ConstellationChan, LoadData};
-use msg::constellation_msg::{NavigationDirection, PipelineId, SubpageId};
+use msg::constellation_msg::{LoadData, NavigationDirection, PipelineId, SubpageId};
 use net_traits::response::HttpsState;
 use script_traits::IFrameSandboxState::{IFrameSandboxed, IFrameUnsandboxed};
 use script_traits::{IFrameLoadInfo, MozBrowserEvent, ScriptMsg as ConstellationMsg};
@@ -120,12 +119,10 @@ impl HTMLIFrameElement {
         }
 
         let window = window_from_node(self);
-        let window = window.r();
         let (new_subpage_id, old_subpage_id) = self.generate_new_subpage_id();
         let new_pipeline_id = self.pipeline_id.get().unwrap();
         let private_iframe = self.privatebrowsing();
 
-        let ConstellationChan(ref chan) = *window.constellation_chan();
         let load_info = IFrameLoadInfo {
             load_data: load_data,
             containing_pipeline_id: window.pipeline(),
@@ -135,7 +132,9 @@ impl HTMLIFrameElement {
             sandbox: sandboxed,
             is_private: private_iframe,
         };
-        chan.send(ConstellationMsg::ScriptLoadedURLInIFrame(load_info)).unwrap();
+        window.constellation_chan()
+              .send(ConstellationMsg::ScriptLoadedURLInIFrame(load_info))
+              .unwrap();
 
         if mozbrowser_enabled() {
             // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowserloadstart
@@ -372,13 +371,11 @@ pub fn Navigate(iframe: &HTMLIFrameElement, direction: NavigationDirection) -> E
     if iframe.Mozbrowser() {
         if iframe.upcast::<Node>().is_in_doc() {
             let window = window_from_node(iframe);
-            let window = window.r();
 
             let pipeline_info = Some((window.pipeline(),
                                       iframe.subpage_id().unwrap()));
-            let ConstellationChan(ref chan) = *window.constellation_chan();
             let msg = ConstellationMsg::Navigate(pipeline_info, direction);
-            chan.send(msg).unwrap();
+            window.constellation_chan().send(msg).unwrap();
         }
 
         Ok(())
@@ -568,7 +565,6 @@ impl VirtualMethods for HTMLIFrameElement {
         // https://html.spec.whatwg.org/multipage/#a-browsing-context-is-discarded
         if let Some(pipeline_id) = self.pipeline_id.get() {
             let window = window_from_node(self);
-            let window = window.r();
 
             // The only reason we're waiting for the iframe to be totally
             // removed is to ensure the script thread can't add iframes faster
@@ -576,7 +572,6 @@ impl VirtualMethods for HTMLIFrameElement {
             //
             // Since most of this cleanup doesn't happen on same-origin
             // iframes, and since that would cause a deadlock, don't do it.
-            let ConstellationChan(ref chan) = *window.constellation_chan();
             let same_origin = {
                 // FIXME(#10968): this should probably match the origin check in
                 //                HTMLIFrameElement::contentDocument.
@@ -591,7 +586,7 @@ impl VirtualMethods for HTMLIFrameElement {
                 (Some(sender), Some(receiver))
             };
             let msg = ConstellationMsg::RemoveIFrame(pipeline_id, sender);
-            chan.send(msg).unwrap();
+            window.constellation_chan().send(msg).unwrap();
             if let Some(receiver) = receiver {
                 receiver.recv().unwrap()
             }
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index c1b2f1b7f76..c2c76dd16e8 100644
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -27,7 +27,7 @@ use dom::node::{document_from_node, window_from_node};
 use dom::nodelist::NodeList;
 use dom::validation::Validatable;
 use dom::virtualmethods::VirtualMethods;
-use msg::constellation_msg::ConstellationChan;
+use ipc_channel::ipc::IpcSender;
 use script_traits::ScriptMsg as ConstellationMsg;
 use std::borrow::ToOwned;
 use std::cell::Cell;
@@ -76,7 +76,7 @@ pub struct HTMLInputElement {
     size: Cell<u32>,
     maxlength: Cell<i32>,
     #[ignore_heap_size_of = "#7193"]
-    textinput: DOMRefCell<TextInput<ConstellationChan<ConstellationMsg>>>,
+    textinput: DOMRefCell<TextInput<IpcSender<ConstellationMsg>>>,
     activation_state: DOMRefCell<InputActivationState>,
     // https://html.spec.whatwg.org/multipage/#concept-input-value-dirty-flag
     value_dirty: Cell<bool>,
diff --git a/components/script/dom/htmllinkelement.rs b/components/script/dom/htmllinkelement.rs
index 023d8a36f58..0a7ebb5de1b 100644
--- a/components/script/dom/htmllinkelement.rs
+++ b/components/script/dom/htmllinkelement.rs
@@ -26,7 +26,6 @@ use hyper::mime::{Mime, TopLevel, SubLevel};
 use ipc_channel::ipc;
 use ipc_channel::router::ROUTER;
 use layout_interface::{LayoutChan, Msg};
-use msg::constellation_msg::ConstellationChan;
 use net_traits::{AsyncResponseListener, AsyncResponseTarget, Metadata, NetworkError};
 use network_listener::{NetworkListener, PreInvoke};
 use script_traits::{MozBrowserEvent, ScriptMsg as ConstellationMsg};
@@ -242,9 +241,8 @@ impl HTMLLinkElement {
         let document = document_from_node(self);
         match document.base_url().join(href) {
             Ok(url) => {
-                let ConstellationChan(ref chan) = *document.window().constellation_chan();
                 let event = ConstellationMsg::NewFavicon(url.clone());
-                chan.send(event).unwrap();
+                document.window().constellation_chan().send(event).unwrap();
 
                 let mozbrowser_event = match *sizes {
                     Some(ref sizes) => MozBrowserEvent::IconChange(rel.to_owned(), url.to_string(), sizes.to_owned()),
diff --git a/components/script/dom/htmltextareaelement.rs b/components/script/dom/htmltextareaelement.rs
index 56296ad9321..516f421f436 100644
--- a/components/script/dom/htmltextareaelement.rs
+++ b/components/script/dom/htmltextareaelement.rs
@@ -23,7 +23,7 @@ use dom::node::{document_from_node, window_from_node};
 use dom::nodelist::NodeList;
 use dom::validation::Validatable;
 use dom::virtualmethods::VirtualMethods;
-use msg::constellation_msg::ConstellationChan;
+use ipc_channel::ipc::IpcSender;
 use script_traits::ScriptMsg as ConstellationMsg;
 use std::cell::Cell;
 use std::ops::Range;
@@ -36,7 +36,7 @@ use util::str::DOMString;
 pub struct HTMLTextAreaElement {
     htmlelement: HTMLElement,
     #[ignore_heap_size_of = "#7193"]
-    textinput: DOMRefCell<TextInput<ConstellationChan<ConstellationMsg>>>,
+    textinput: DOMRefCell<TextInput<IpcSender<ConstellationMsg>>>,
     // https://html.spec.whatwg.org/multipage/#concept-textarea-dirty
     value_changed: Cell<bool>,
 }
diff --git a/components/script/dom/webglrenderingcontext.rs b/components/script/dom/webglrenderingcontext.rs
index 1141637f908..241aa0aa60e 100644
--- a/components/script/dom/webglrenderingcontext.rs
+++ b/components/script/dom/webglrenderingcontext.rs
@@ -95,8 +95,7 @@ impl WebGLRenderingContext {
                      -> Result<WebGLRenderingContext, String> {
         let (sender, receiver) = ipc::channel().unwrap();
         let constellation_chan = global.constellation_chan();
-        constellation_chan.0
-                          .send(ConstellationMsg::CreateWebGLPaintThread(size, attrs, sender))
+        constellation_chan.send(ConstellationMsg::CreateWebGLPaintThread(size, attrs, sender))
                           .unwrap();
         let result = receiver.recv().unwrap();
 
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 727ae7d8c32..e665add7928 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -42,7 +42,7 @@ use js::rust::Runtime;
 use layout_interface::{ContentBoxResponse, ContentBoxesResponse, ResolvedStyleResponse, ScriptReflow};
 use layout_interface::{LayoutChan, LayoutRPC, Msg, Reflow, ReflowQueryType, MarginStyleResponse};
 use libc;
-use msg::constellation_msg::{ConstellationChan, LoadData, PanicMsg, PipelineId, SubpageId};
+use msg::constellation_msg::{LoadData, PanicMsg, PipelineId, SubpageId};
 use msg::constellation_msg::{WindowSizeData, WindowSizeType};
 use msg::webdriver_msg::{WebDriverJSError, WebDriverJSResult};
 use net_traits::ResourceThread;
@@ -228,7 +228,7 @@ pub struct Window {
 
     /// A handle for communicating messages to the constellation thread.
     #[ignore_heap_size_of = "channels are hard"]
-    constellation_chan: ConstellationChan<ConstellationMsg>,
+    constellation_chan: IpcSender<ConstellationMsg>,
 
     /// Pending scroll to fragment event, if any
     fragment_name: DOMRefCell<Option<String>>,
@@ -449,7 +449,7 @@ impl WindowMethods for Window {
         stderr.flush().unwrap();
 
         let (sender, receiver) = ipc::channel().unwrap();
-        self.constellation_chan().0.send(ConstellationMsg::Alert(self.pipeline(), s.to_string(), sender)).unwrap();
+        self.constellation_chan().send(ConstellationMsg::Alert(self.pipeline(), s.to_string(), sender)).unwrap();
 
         let should_display_alert_dialog = receiver.recv().unwrap();
         if should_display_alert_dialog {
@@ -1120,7 +1120,7 @@ impl Window {
 
             if ready_state == DocumentReadyState::Complete && !reftest_wait {
                 let event = ConstellationMsg::SetDocumentState(self.id, DocumentState::Idle);
-                self.constellation_chan().0.send(event).unwrap();
+                self.constellation_chan().send(event).unwrap();
             }
         }
     }
@@ -1296,7 +1296,7 @@ impl Window {
         &self.layout_chan
     }
 
-    pub fn constellation_chan(&self) -> &ConstellationChan<ConstellationMsg> {
+    pub fn constellation_chan(&self) -> &IpcSender<ConstellationMsg> {
         &self.constellation_chan
     }
 
@@ -1459,7 +1459,7 @@ impl Window {
                mem_profiler_chan: mem::ProfilerChan,
                time_profiler_chan: ProfilerChan,
                devtools_chan: Option<IpcSender<ScriptToDevtoolsControlMsg>>,
-               constellation_chan: ConstellationChan<ConstellationMsg>,
+               constellation_chan: IpcSender<ConstellationMsg>,
                control_chan: IpcSender<ConstellationControlMsg>,
                scheduler_chan: IpcSender<TimerEventRequest>,
                panic_chan: IpcSender<PanicMsg>,
diff --git a/components/script/dom/workerglobalscope.rs b/components/script/dom/workerglobalscope.rs
index 618da932d44..8b5b2637179 100644
--- a/components/script/dom/workerglobalscope.rs
+++ b/components/script/dom/workerglobalscope.rs
@@ -21,7 +21,7 @@ use ipc_channel::ipc::IpcSender;
 use js::jsapi::{HandleValue, JSContext, JSRuntime, RootedValue};
 use js::jsval::UndefinedValue;
 use js::rust::Runtime;
-use msg::constellation_msg::{ConstellationChan, PanicMsg, PipelineId};
+use msg::constellation_msg::{PanicMsg, PipelineId};
 use net_traits::{LoadContext, ResourceThread, load_whole_resource};
 use profile_traits::{mem, time};
 use script_runtime::{CommonScriptMsg, ScriptChan, ScriptPort};
@@ -48,7 +48,7 @@ pub struct WorkerGlobalScopeInit {
     pub time_profiler_chan: time::ProfilerChan,
     pub to_devtools_sender: Option<IpcSender<ScriptToDevtoolsControlMsg>>,
     pub from_devtools_sender: Option<IpcSender<DevtoolScriptControlMsg>>,
-    pub constellation_chan: ConstellationChan<ConstellationMsg>,
+    pub constellation_chan: IpcSender<ConstellationMsg>,
     pub scheduler_chan: IpcSender<TimerEventRequest>,
     pub panic_chan: IpcSender<PanicMsg>,
     pub worker_id: WorkerId,
@@ -94,7 +94,7 @@ pub struct WorkerGlobalScope {
     devtools_wants_updates: Cell<bool>,
 
     #[ignore_heap_size_of = "Defined in std"]
-    constellation_chan: ConstellationChan<ConstellationMsg>,
+    constellation_chan: IpcSender<ConstellationMsg>,
 
     #[ignore_heap_size_of = "Defined in std"]
     scheduler_chan: IpcSender<TimerEventRequest>,
@@ -156,7 +156,7 @@ impl WorkerGlobalScope {
         &self.from_devtools_receiver
     }
 
-    pub fn constellation_chan(&self) -> &ConstellationChan<ConstellationMsg> {
+    pub fn constellation_chan(&self) -> &IpcSender<ConstellationMsg> {
         &self.constellation_chan
     }
 
diff --git a/components/script/layout_interface.rs b/components/script/layout_interface.rs
index 2a9598fcc8b..2a6e0b1d79a 100644
--- a/components/script/layout_interface.rs
+++ b/components/script/layout_interface.rs
@@ -12,8 +12,7 @@ use euclid::point::Point2D;
 use euclid::rect::Rect;
 use gfx_traits::{Epoch, LayerId};
 use ipc_channel::ipc::{IpcReceiver, IpcSender};
-use msg::constellation_msg::{ConstellationChan, PanicMsg, PipelineId};
-use msg::constellation_msg::{WindowSizeData};
+use msg::constellation_msg::{PanicMsg, PipelineId, WindowSizeData};
 use net_traits::image_cache_thread::ImageCacheThread;
 use profile_traits::mem::ReportsChan;
 use script_traits::{ConstellationControlMsg, LayoutControlMsg, LayoutMsg as ConstellationMsg};
@@ -262,8 +261,8 @@ pub struct NewLayoutThreadInfo {
     pub is_parent: bool,
     pub layout_pair: OpaqueScriptLayoutChannel,
     pub pipeline_port: IpcReceiver<LayoutControlMsg>,
-    pub constellation_chan: ConstellationChan<ConstellationMsg>,
-    pub panic_chan: ConstellationChan<PanicMsg>,
+    pub constellation_chan: IpcSender<ConstellationMsg>,
+    pub panic_chan: IpcSender<PanicMsg>,
     pub script_chan: IpcSender<ConstellationControlMsg>,
     pub image_cache_thread: ImageCacheThread,
     pub paint_chan: OptionalOpaqueIpcSender,
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 0e3d9935435..0fe4ab3ea3c 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -59,8 +59,7 @@ use js::rust::Runtime;
 use layout_interface::{ReflowQueryType};
 use layout_interface::{self, LayoutChan, NewLayoutThreadInfo, ScriptLayoutChan};
 use mem::heap_size_of_self_and_children;
-use msg::constellation_msg::{ConstellationChan, LoadData, PanicMsg};
-use msg::constellation_msg::{PipelineId, PipelineNamespace};
+use msg::constellation_msg::{LoadData, PanicMsg, PipelineId, PipelineNamespace};
 use msg::constellation_msg::{SubpageId, WindowSizeData, WindowSizeType};
 use msg::webdriver_msg::WebDriverScriptCommand;
 use net_traits::LoadData as NetLoadData;
@@ -342,10 +341,10 @@ pub struct ScriptThread {
     control_port: Receiver<ConstellationControlMsg>,
 
     /// For communicating load url messages to the constellation
-    constellation_chan: ConstellationChan<ConstellationMsg>,
+    constellation_chan: IpcSender<ConstellationMsg>,
 
     /// For communicating layout messages to the constellation
-    layout_to_constellation_chan: ConstellationChan<LayoutMsg>,
+    layout_to_constellation_chan: IpcSender<LayoutMsg>,
 
     /// A handle to the compositor for communicating ready state messages.
     compositor: DOMRefCell<IpcSender<ScriptToCompositorMsg>>,
@@ -438,7 +437,7 @@ impl ScriptThreadFactory for ScriptThread {
               state: InitialScriptState,
               layout_chan: &OpaqueScriptLayoutChannel,
               load_data: LoadData) {
-        let ConstellationChan(panic_chan) = state.panic_chan.clone();
+        let panic_chan = state.panic_chan.clone();
         let (script_chan, script_port) = channel();
         let layout_chan = LayoutChan(layout_chan.sender());
         let pipeline_id = state.id;
@@ -577,7 +576,7 @@ impl ScriptThread {
             compositor: DOMRefCell::new(state.compositor),
             time_profiler_chan: state.time_profiler_chan,
             mem_profiler_chan: state.mem_profiler_chan,
-            panic_chan: state.panic_chan.0,
+            panic_chan: state.panic_chan,
 
             devtools_chan: state.devtools_chan,
             devtools_port: devtools_port,
@@ -1134,8 +1133,7 @@ impl ScriptThread {
         let handler = box DocumentProgressHandler::new(Trusted::new(doc));
         self.dom_manipulation_task_source.queue(DOMManipulationTask::DocumentProgress(handler)).unwrap();
 
-        let ConstellationChan(ref chan) = self.constellation_chan;
-        chan.send(ConstellationMsg::LoadComplete(pipeline)).unwrap();
+        self.constellation_chan.send(ConstellationMsg::LoadComplete(pipeline)).unwrap();
     }
 
     fn collect_reports(&self, reports_chan: ReportsChan) {
@@ -1398,8 +1396,9 @@ impl ScriptThread {
             chan.send(layout_interface::Msg::SetFinalUrl(final_url.clone())).unwrap();
 
             // update the pipeline url
-            let ConstellationChan(ref chan) = self.constellation_chan;
-            chan.send(ConstellationMsg::SetFinalUrl(incomplete.pipeline_id, final_url.clone())).unwrap();
+            self.constellation_chan
+                .send(ConstellationMsg::SetFinalUrl(incomplete.pipeline_id, final_url.clone()))
+                .unwrap();
         }
         debug!("ScriptThread: loading {} on pipeline {:?}", incomplete.url, incomplete.pipeline_id);
 
@@ -1569,8 +1568,9 @@ impl ScriptThread {
         }
         document.set_ready_state(DocumentReadyState::Loading);
 
-        let ConstellationChan(ref chan) = self.constellation_chan;
-        chan.send(ConstellationMsg::ActivateDocument(incomplete.pipeline_id)).unwrap();
+        self.constellation_chan
+            .send(ConstellationMsg::ActivateDocument(incomplete.pipeline_id))
+            .unwrap();
 
         // Notify devtools that a new script global exists.
         self.notify_devtools(document.Title(), final_url.clone(), (browsing_context.pipeline(), None));
@@ -1729,8 +1729,7 @@ impl ScriptThread {
                                            });
 
                         let event = ConstellationMsg::NodeStatus(status);
-                        let ConstellationChan(ref chan) = self.constellation_chan;
-                        chan.send(event).unwrap();
+                        self.constellation_chan.send(event).unwrap();
 
                         state_already_changed = true;
                     }
@@ -1744,8 +1743,7 @@ impl ScriptThread {
                                                .filter_map(Root::downcast::<HTMLAnchorElement>)
                                                .next() {
                             let event = ConstellationMsg::NodeStatus(None);
-                            let ConstellationChan(ref chan) = self.constellation_chan;
-                            chan.send(event).unwrap();
+                            self.constellation_chan.send(event).unwrap();
                         }
                     }
                 }
@@ -1844,8 +1842,9 @@ impl ScriptThread {
                 }
             }
             None => {
-                let ConstellationChan(ref const_chan) = self.constellation_chan;
-                const_chan.send(ConstellationMsg::LoadUrl(pipeline_id, load_data)).unwrap();
+                self.constellation_chan
+                    .send(ConstellationMsg::LoadUrl(pipeline_id, load_data))
+                    .unwrap();
             }
         }
     }