Make iframes block the enclosing document's load event. Fixes #6663.

components/script/dom/htmliframeelement.rs

@@ -2,7 +2,9 @@
  * 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 document_loader::{LoadType, LoadBlocker};
 use dom::attr::{Attr, AttrValue};
+use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::BrowserElementBinding::BrowserElementIconChangeEventDetail;
 use dom::bindings::codegen::Bindings::BrowserElementBinding::BrowserElementSecurityChangeDetail;
 use dom::bindings::codegen::Bindings::BrowserElementBinding::BrowserShowModalPromptEventDetail;
@@ -21,7 +23,7 @@ use dom::element::{AttributeMutation, Element, RawLayoutElementHelpers};
 use dom::event::Event;
 use dom::eventtarget::EventTarget;
 use dom::htmlelement::HTMLElement;
-use dom::node::{Node, UnbindContext, window_from_node};
+use dom::node::{Node, UnbindContext, window_from_node, document_from_node};
 use dom::urlhelper::UrlHelper;
 use dom::virtualmethods::VirtualMethods;
 use dom::window::{ReflowReason, Window};
@@ -64,6 +66,7 @@ pub struct HTMLIFrameElement {
     subpage_id: Cell<Option<SubpageId>>,
     containing_page_pipeline_id: Cell<Option<PipelineId>>,
     sandbox: Cell<Option<u8>>,
+    load_blocker: DOMRefCell<Option<LoadBlocker>>,
 }
 
 impl HTMLIFrameElement {
@@ -101,6 +104,20 @@ impl HTMLIFrameElement {
             IFrameUnsandboxed
         };
 
+        let document = document_from_node(self);
+
+        let mut load_blocker = self.load_blocker.borrow_mut();
+        // Any oustanding load is finished from the point of view of the blocked
+        // document; the new navigation will continue blocking it.
+        LoadBlocker::terminate(&mut load_blocker);
+
+        //TODO(#9592): Deal with the case where an iframe is being reloaded so url is None.
+        //      The iframe should always have access to the nested context's active
+        //      document URL through the browsing context.
+        if let Some(ref url) = url {
+            *load_blocker = Some(LoadBlocker::new(&*document, LoadType::Subframe(url.clone())));
+        }
+
         let window = window_from_node(self);
         let window = window.r();
         let (new_subpage_id, old_subpage_id) = self.generate_new_subpage_id();
@@ -173,6 +190,7 @@ impl HTMLIFrameElement {
             subpage_id: Cell::new(None),
             containing_page_pipeline_id: Cell::new(None),
             sandbox: Cell::new(None),
+            load_blocker: DOMRefCell::new(None),
         }
     }
 
@@ -204,7 +222,11 @@ impl HTMLIFrameElement {
     }
 
     /// https://html.spec.whatwg.org/multipage/#iframe-load-event-steps steps 1-4
-    pub fn iframe_load_event_steps(&self) {
+    pub fn iframe_load_event_steps(&self, loaded_pipeline: PipelineId) {
+        // TODO(#9592): assert that the load blocker is present at all times when we
+        //              can guarantee that it's created for the case of iframe.reload().
+        assert_eq!(loaded_pipeline, self.pipeline().unwrap());
+
         // TODO A cross-origin child document would not be easily accessible
         //      from this script thread. It's unclear how to implement
         //      steps 2, 3, and 5 efficiently in this case.
@@ -213,6 +235,10 @@ impl HTMLIFrameElement {
 
         // Step 4
         self.upcast::<EventTarget>().fire_simple_event("load");
+
+        let mut blocker = self.load_blocker.borrow_mut();
+        LoadBlocker::terminate(&mut blocker);
+
         // TODO Step 5 - unset child document `mut iframe load` flag
 
         let window = window_from_node(self);
@@ -510,6 +536,9 @@ impl VirtualMethods for HTMLIFrameElement {
     fn unbind_from_tree(&self, context: &UnbindContext) {
         self.super_type().unwrap().unbind_from_tree(context);
 
+        let mut blocker = self.load_blocker.borrow_mut();
+        LoadBlocker::terminate(&mut blocker);
+
         // 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);