First part of refactoring constellation to support iframe navigation.

The history is now recorded per frame, but needs to be exposed in a followup PR.

Also fixes a race condition that occurs loading iframes under heavy CPU load.

This ensures that iframes never do a reflow / layout until they have a valid
window size set from their parent frame.

components/script/dom/htmlformelement.rs

@@ -215,7 +215,7 @@ impl<'a> HTMLFormElementHelpers for JSRef<'a, HTMLFormElement> {
         }
 
         // This is wrong. https://html.spec.whatwg.org/multipage/forms.html#planned-navigation
-        win.r().script_chan().send(ScriptMsg::TriggerLoad(win.r().pipeline(), load_data)).unwrap();
+        win.r().script_chan().send(ScriptMsg::Navigate(win.r().pipeline(), load_data)).unwrap();
     }
 
     fn get_form_dataset<'b>(self, submitter: Option<FormSubmitter<'b>>) -> Vec<FormDatum> {

components/script/dom/htmliframeelement.rs

@@ -63,6 +63,7 @@ pub trait HTMLIFrameElementHelpers {
     /// http://www.whatwg.org/html/#process-the-iframe-attributes
     fn process_the_iframe_attributes(self);
     fn generate_new_subpage_id(self) -> (SubpageId, Option<SubpageId>);
+    fn navigate_child_browsing_context(self, url: Url);
 }
 
 impl<'a> HTMLIFrameElementHelpers for JSRef<'a, HTMLIFrameElement> {
@@ -92,12 +93,7 @@ impl<'a> HTMLIFrameElementHelpers for JSRef<'a, HTMLIFrameElement> {
         (subpage_id, old_subpage_id)
     }
 
-    fn process_the_iframe_attributes(self) {
-        let url = match self.get_url() {
-            Some(url) => url.clone(),
-            None => Url::parse("about:blank").unwrap(),
-        };
-
+    fn navigate_child_browsing_context(self, url: Url) {
         let sandboxed = if self.is_sandboxed() {
             IFrameSandboxed
         } else {
@@ -111,11 +107,20 @@ impl<'a> HTMLIFrameElementHelpers for JSRef<'a, HTMLIFrameElement> {
         self.containing_page_pipeline_id.set(Some(window.pipeline()));
 
         let ConstellationChan(ref chan) = window.constellation_chan();
-    chan.send(ConstellationMsg::ScriptLoadedURLInIFrame(url,
-                                                        window.pipeline(),
-                                                        new_subpage_id,
-                                                        old_subpage_id,
-                                                        sandboxed)).unwrap();
+        chan.send(ConstellationMsg::ScriptLoadedURLInIFrame(url,
+                                                            window.pipeline(),
+                                                            new_subpage_id,
+                                                            old_subpage_id,
+                                                            sandboxed)).unwrap();
+    }
+
+    fn process_the_iframe_attributes(self) {
+        let url = match self.get_url() {
+            Some(url) => url.clone(),
+            None => Url::parse("about:blank").unwrap(),
+        };
+
+        self.navigate_child_browsing_context(url);
     }
 }
 

components/script/dom/window.rs

@@ -135,7 +135,7 @@ pub struct Window {
     layout_join_port: DOMRefCell<Option<Receiver<()>>>,
 
     /// The current size of the window, in pixels.
-    window_size: Cell<WindowSizeData>,
+    window_size: Cell<Option<WindowSizeData>>,
 
     /// Associated resource task for use by DOM objects like XMLHttpRequest
     resource_task: ResourceTask,
@@ -428,7 +428,7 @@ pub trait WindowHelpers {
     fn set_fragment_name(self, fragment: Option<String>);
     fn steal_fragment_name(self) -> Option<String>;
     fn set_window_size(self, size: WindowSizeData);
-    fn window_size(self) -> WindowSizeData;
+    fn window_size(self) -> Option<WindowSizeData>;
     fn get_url(self) -> Url;
     fn resource_task(self) -> ResourceTask;
     fn devtools_chan(self) -> Option<DevtoolsControlChan>;
@@ -517,6 +517,11 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
             return
         }
 
+        let window_size = match self.window_size.get() {
+            Some(window_size) => window_size,
+            None => return,
+        };
+
         // Layout will let us know when it's done.
         let (join_chan, join_port) = channel();
 
@@ -528,8 +533,6 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
         let last_reflow_id = &self.last_reflow_id;
         last_reflow_id.set(last_reflow_id.get() + 1);
 
-        let window_size = self.window_size.get();
-
         // On debug mode, print the reflow event information.
         if opts::get().relayout_event {
             debug_reflow_events(&goal, &query_type, &reason);
@@ -607,7 +610,7 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
     }
 
     fn handle_resize_inactive_msg(self, new_size: WindowSizeData) {
-        self.window_size.set(new_size);
+        self.window_size.set(Some(new_size));
     }
 
     fn init_browser_context(self, doc: JSRef<Document>, frame_element: Option<JSRef<Element>>) {
@@ -626,7 +629,7 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
                 self.script_chan.send(ScriptMsg::TriggerFragment(self.id, fragment)).unwrap();
             },
             None => {
-                self.script_chan.send(ScriptMsg::TriggerLoad(self.id, LoadData::new(url))).unwrap();
+                self.script_chan.send(ScriptMsg::Navigate(self.id, LoadData::new(url))).unwrap();
             }
         }
     }
@@ -645,10 +648,10 @@ impl<'a> WindowHelpers for JSRef<'a, Window> {
     }
 
     fn set_window_size(self, size: WindowSizeData) {
-        self.window_size.set(size);
+        self.window_size.set(Some(size));
     }
 
-    fn window_size(self) -> WindowSizeData {
+    fn window_size(self) -> Option<WindowSizeData> {
         self.window_size.get()
     }
 
@@ -755,7 +758,7 @@ impl Window {
                layout_chan: LayoutChan,
                id: PipelineId,
                subpage_id: Option<SubpageId>,
-               window_size: WindowSizeData)
+               window_size: Option<WindowSizeData>)
                -> Temporary<Window> {
         let layout_rpc: Box<LayoutRPC> = {
             let (rpc_send, rpc_recv) = channel();