Auto merge of #16506 - cbrewster:about_chaos, r=asajeffrey

Make non-initial about:blank loads async

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #14856 (github issue number if applicable).

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components/compositing/compositor.rs

@@ -903,7 +903,8 @@ impl<Window: WindowMethods> IOCompositor<Window> {
         match ServoUrl::parse(&url_string) {
             Ok(url) => {
                 let msg = match self.root_pipeline {
-                    Some(ref pipeline) => ConstellationMsg::LoadUrl(pipeline.id, LoadData::new(url, None, None)),
+                    Some(ref pipeline) =>
+                        ConstellationMsg::LoadUrl(pipeline.id, LoadData::new(url, Some(pipeline.id), None, None)),
                     None => ConstellationMsg::InitLoadUrl(url)
                 };
                 if let Err(e) = self.constellation_chan.send(msg) {

components/constellation/constellation.rs

@@ -101,7 +101,7 @@ use script_traits::{IFrameLoadInfo, IFrameLoadInfoWithData, IFrameSandboxState,
 use script_traits::{LayoutMsg as FromLayoutMsg, ScriptMsg as FromScriptMsg, ScriptThreadFactory};
 use script_traits::{LogEntry, ServiceWorkerMsg, webdriver_msg};
 use script_traits::{MozBrowserErrorType, MozBrowserEvent, WebDriverCommandMsg, WindowSizeData};
-use script_traits::{SWManagerMsg, ScopeThings, WindowSizeType};
+use script_traits::{SWManagerMsg, ScopeThings, UpdatePipelineIdReason, WindowSizeType};
 use serde::{Deserialize, Serialize};
 use servo_config::opts;
 use servo_config::prefs::PREFS;
@@ -599,7 +599,11 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
 
         let (event_loop, host) = match sandbox {
             IFrameSandboxState::IFrameSandboxed => (None, None),
-            IFrameSandboxState::IFrameUnsandboxed => match reg_host(&load_data.url) {
+            IFrameSandboxState::IFrameUnsandboxed => {
+                // If this is an about:blank load, it must share the creator's event loop.
+                // This must match the logic in the script thread when determining the proper origin.
+                if load_data.url.as_str() != "about:blank" {
+                    match reg_host(&load_data.url) {
                         None => (None, None),
                         Some(host) => {
                             let event_loop = self.event_loops.get(&top_level_frame_id)
@@ -610,6 +614,16 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                                 Some(event_loop) => (Some(event_loop.clone()), None),
                             }
                         },
+                    }
+                } else if let Some(parent) = parent_info
+                        .and_then(|(pipeline_id, _)| self.pipelines.get(&pipeline_id)) {
+                    (Some(parent.event_loop.clone()), None)
+                } else if let Some(creator) = load_data.creator_pipeline_id
+                        .and_then(|pipeline_id| self.pipelines.get(&pipeline_id)) {
+                    (Some(creator.event_loop.clone()), None)
+                } else {
+                    (None, None)
+                }
             },
         };
 
@@ -735,7 +749,10 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     }
 
     /// Create a new frame and update the internal bookkeeping.
-    fn new_frame(&mut self, frame_id: FrameId, pipeline_id: PipelineId, load_data: LoadData) {
+    fn new_frame(&mut self,
+                 frame_id: FrameId,
+                 pipeline_id: PipelineId,
+                 load_data: LoadData) {
         let frame = Frame::new(frame_id, pipeline_id, load_data);
         self.frames.insert(frame_id, frame);
 
@@ -915,11 +932,11 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                        load_info.info.new_pipeline_id);
                 self.handle_script_loaded_url_in_iframe_msg(load_info);
             }
-            FromScriptMsg::ScriptLoadedAboutBlankInIFrame(load_info, lc) => {
+            FromScriptMsg::ScriptNewIFrame(load_info, layout_sender) => {
                 debug!("constellation got loaded `about:blank` in iframe message {:?} {:?}",
                        load_info.parent_pipeline_id,
                        load_info.new_pipeline_id);
-                self.handle_script_loaded_about_blank_in_iframe_msg(load_info, lc);
+                self.handle_script_new_iframe(load_info, layout_sender);
             }
             FromScriptMsg::ChangeRunningAnimationsState(pipeline_id, animation_state) => {
                 self.handle_change_running_animations_state(pipeline_id, animation_state)
@@ -1277,10 +1294,19 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         // Notify the browser chrome that the pipeline has failed
         self.trigger_mozbrowsererror(top_level_frame_id, reason, backtrace);
 
-        let pipeline_id = self.frames.get(&top_level_frame_id).map(|frame| frame.pipeline_id);
+        let (window_size, pipeline_id) = {
-        let pipeline_url = pipeline_id.and_then(|id| self.pipelines.get(&id).map(|pipeline| pipeline.url.clone()));
+            let frame = self.frames.get(&top_level_frame_id);
-        let parent_info = pipeline_id.and_then(|id| self.pipelines.get(&id).and_then(|pipeline| pipeline.parent_info));
+            let window_size = frame.and_then(|frame| frame.size);
-        let window_size = pipeline_id.and_then(|id| self.pipelines.get(&id).and_then(|pipeline| pipeline.size));
+            let pipeline_id = frame.map(|frame| frame.pipeline_id);
+            (window_size, pipeline_id)
+        };
+
+        let (pipeline_url, parent_info) = {
+            let pipeline = pipeline_id.and_then(|id| self.pipelines.get(&id));
+            let pipeline_url = pipeline.map(|pipeline| pipeline.url.clone());
+            let parent_info = pipeline.and_then(|pipeline| pipeline.parent_info);
+            (pipeline_url, parent_info)
+        };
 
         self.close_frame_children(top_level_frame_id, DiscardBrowsingContext::No, ExitPipelineMode::Force);
 
@@ -1295,7 +1321,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         warn!("creating replacement pipeline for about:failure");
 
         let new_pipeline_id = PipelineId::new();
-        let load_data = LoadData::new(failure_url, None, None);
+        let load_data = LoadData::new(failure_url, None, None, None);
         let sandbox = IFrameSandboxState::IFrameSandboxed;
         self.new_pipeline(new_pipeline_id, top_level_frame_id, parent_info,
                           window_size, load_data.clone(), sandbox, false);
@@ -1340,7 +1366,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         let window_size = self.window_size.initial_viewport;
         let root_pipeline_id = PipelineId::new();
         let root_frame_id = self.root_frame_id;
-        let load_data = LoadData::new(url.clone(), None, None);
+        let load_data = LoadData::new(url.clone(), None, None, None);
         let sandbox = IFrameSandboxState::IFrameUnsandboxed;
         self.new_pipeline(root_pipeline_id, root_frame_id, None, Some(window_size), load_data.clone(), sandbox, false);
         self.handle_load_start_msg(root_pipeline_id);
@@ -1353,29 +1379,14 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     }
 
     fn handle_frame_size_msg(&mut self,
-                             iframe_sizes: Vec<(PipelineId, TypedSize2D<f32, CSSPixel>)>) {
+                             iframe_sizes: Vec<(FrameId, TypedSize2D<f32, CSSPixel>)>) {
-        for (pipeline_id, size) in iframe_sizes {
+        for (frame_id, size) in iframe_sizes {
-            let result = {
+            let window_size = WindowSizeData {
-                let pipeline = match self.pipelines.get_mut(&pipeline_id) {
-                    Some(pipeline) => pipeline,
-                    None => continue,
-                };
-
-                if pipeline.size == Some(size) {
-                    continue;
-                }
-
-                pipeline.size = Some(size);
-                let msg = ConstellationControlMsg::Resize(pipeline_id, WindowSizeData {
                 initial_viewport: size,
                 device_pixel_ratio: self.window_size.device_pixel_ratio,
-                }, WindowSizeType::Initial);
-
-                pipeline.event_loop.send(msg)
             };
-            if let Err(e) = result {
+
-                self.handle_send_error(pipeline_id, e);
+            self.resize_frame(window_size, WindowSizeType::Initial, frame_id);
-            }
         }
     }
 
@@ -1423,12 +1434,12 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 };
 
                 // TODO - loaddata here should have referrer info (not None, None)
-                LoadData::new(url, None, None)
+                LoadData::new(url, Some(source_pipeline.id), None, None)
             });
 
             let is_private = load_info.info.is_private || source_pipeline.is_private;
 
-            let window_size = old_pipeline.and_then(|old_pipeline| old_pipeline.size);
+            let window_size = self.frames.get(&load_info.info.frame_id).and_then(|frame| frame.size);
 
             (load_data, window_size, is_private)
         };
@@ -1456,7 +1467,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                           is_private);
     }
 
-    fn handle_script_loaded_about_blank_in_iframe_msg(&mut self,
+    fn handle_script_new_iframe(&mut self,
                                 load_info: IFrameLoadInfo,
                                 layout_sender: IpcSender<LayoutControlMsg>) {
         let IFrameLoadInfo {
@@ -1486,12 +1497,11 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                           self.compositor_proxy.clone_compositor_proxy(),
                           is_private || parent_pipeline.is_private,
                           url.clone(),
-                          None,
                           parent_pipeline.visible)
         };
 
         // TODO: Referrer?
-        let load_data = LoadData::new(url, None, None);
+        let load_data = LoadData::new(url, Some(parent_pipeline_id), None, None);
 
         let replace_instant = if replace {
             self.frames.get(&frame_id).map(|frame| frame.instant)
@@ -1641,7 +1651,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 // changes would be overridden by changing the subframe associated with source_id.
 
                 // Create the new pipeline
-                let window_size = self.pipelines.get(&source_id).and_then(|source| source.size);
+                let window_size = self.frames.get(&root_frame_id).and_then(|frame| frame.size);
                 let new_pipeline_id = PipelineId::new();
                 let sandbox = IFrameSandboxState::IFrameUnsandboxed;
                 let replace_instant = if replace {
@@ -1959,7 +1969,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             },
             WebDriverCommandMsg::Refresh(pipeline_id, reply) => {
                 let load_data = match self.pipelines.get(&pipeline_id) {
-                    Some(pipeline) => LoadData::new(pipeline.url.clone(), None, None),
+                    Some(pipeline) => LoadData::new(pipeline.url.clone(), None, None, None),
                     None => return warn!("Pipeline {:?} Refresh after closure.", pipeline_id),
                 };
                 self.load_url_for_webdriver(pipeline_id, load_data, reply, true);
@@ -2019,8 +2029,8 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 let load_data = entry.load_data;
                 let (parent_info, window_size, is_private) = match self.frames.get(&frame_id) {
                     Some(frame) => match self.pipelines.get(&frame.pipeline_id) {
-                        Some(pipeline) => (pipeline.parent_info, pipeline.size, pipeline.is_private),
+                        Some(pipeline) => (pipeline.parent_info, frame.size, pipeline.is_private),
-                        None => (None, None, false),
+                        None => (None, frame.size, false),
                     },
                     None => return warn!("no frame to traverse"),
                 };
@@ -2101,7 +2111,8 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         // Update the owning iframe to point to the new pipeline id.
         // This makes things like contentDocument work correctly.
         if let Some((parent_pipeline_id, _)) = parent_info {
-            let msg = ConstellationControlMsg::UpdatePipelineId(parent_pipeline_id, frame_id, pipeline_id);
+            let msg = ConstellationControlMsg::UpdatePipelineId(parent_pipeline_id,
+                frame_id, pipeline_id, UpdatePipelineIdReason::Traversal);
             let result = match self.pipelines.get(&parent_pipeline_id) {
                 None => return warn!("Pipeline {:?} child traversed after closure.", parent_pipeline_id),
                 Some(pipeline) => pipeline.event_loop.send(msg),
@@ -2245,7 +2256,9 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         }
 
         if new_frame {
-            self.new_frame(frame_change.frame_id, frame_change.new_pipeline_id, frame_change.load_data);
+            self.new_frame(frame_change.frame_id,
+                           frame_change.new_pipeline_id,
+                           frame_change.load_data);
             self.update_activity(frame_change.new_pipeline_id);
             self.notify_history_changed(frame_change.new_pipeline_id);
         };
@@ -2275,7 +2288,8 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         if let Some(pipeline) = self.pipelines.get(&pipeline_id) {
             if let Some((parent_pipeline_id, _)) = pipeline.parent_info {
                 if let Some(parent_pipeline) = self.pipelines.get(&parent_pipeline_id) {
-                    let msg = ConstellationControlMsg::FramedContentChanged(parent_pipeline_id, pipeline.frame_id);
+                    let msg = ConstellationControlMsg::UpdatePipelineId(parent_pipeline_id,
+                        pipeline.frame_id, pipeline_id, UpdatePipelineIdReason::Navigation);
                     let _ = parent_pipeline.event_loop.send(msg);
                 }
             }
@@ -2298,45 +2312,8 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     fn handle_window_size_msg(&mut self, new_size: WindowSizeData, size_type: WindowSizeType) {
         debug!("handle_window_size_msg: {:?}", new_size.initial_viewport.to_untyped());
 
-        if let Some(frame) = self.frames.get(&self.root_frame_id) {
+        let frame_id = self.root_frame_id;
-            // Send Resize (or ResizeInactive) messages to each
+        self.resize_frame(new_size, size_type, frame_id);
-            // pipeline in the frame tree.
-            let pipeline_id = frame.pipeline_id;
-            let pipeline = match self.pipelines.get(&pipeline_id) {
-                None => return warn!("Pipeline {:?} resized after closing.", pipeline_id),
-                Some(pipeline) => pipeline,
-            };
-            let _ = pipeline.event_loop.send(ConstellationControlMsg::Resize(
-                pipeline.id,
-                new_size,
-                size_type
-            ));
-            let pipelines = frame.prev.iter().chain(frame.next.iter())
-                .filter_map(|entry| entry.pipeline_id)
-                .filter_map(|pipeline_id| self.pipelines.get(&pipeline_id));
-            for pipeline in pipelines {
-                let _ = pipeline.event_loop.send(ConstellationControlMsg::ResizeInactive(
-                    pipeline.id,
-                    new_size
-                ));
-            }
-        }
-
-        // Send resize message to any pending pipelines that aren't loaded yet.
-        for pending_frame in &self.pending_frames {
-            let pipeline_id = pending_frame.new_pipeline_id;
-            let pipeline = match self.pipelines.get(&pipeline_id) {
-                None => { warn!("Pending pipeline {:?} is closed", pipeline_id); continue; }
-                Some(pipeline) => pipeline,
-            };
-            if pipeline.parent_info.is_none() {
-                let _ = pipeline.event_loop.send(ConstellationControlMsg::Resize(
-                    pipeline.id,
-                    new_size,
-                    size_type
-                ));
-            }
-        }
 
         if let Some(resize_channel) = self.webdriver.resize_channel.take() {
             let _ = resize_channel.send(new_size);
@@ -2422,7 +2399,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             // size for the pipeline, then its painting should be up to date. If the constellation
             // *hasn't* received a size, it could be that the layer was hidden by script before the
             // compositor discovered it, so we just don't check the layer.
-            if let Some(size) = pipeline.size {
+            if let Some(size) = frame.size {
                 // If the rectangle for this pipeline is zero sized, it will
                 // never be painted. In this case, don't query the layout
                 // thread as it won't contribute to the final output image.
@@ -2509,6 +2486,54 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         self.set_activity(pipeline_id, self.get_activity(pipeline_id));
     }
 
+    /// Handle updating the size of a frame. This notifies every pipeline in the frame of the new
+    /// size.
+    fn resize_frame(&mut self, new_size: WindowSizeData, size_type: WindowSizeType, frame_id: FrameId) {
+        if let Some(frame) = self.frames.get_mut(&frame_id) {
+            frame.size = Some(new_size.initial_viewport);
+        }
+
+        if let Some(frame) = self.frames.get(&frame_id) {
+            // Send Resize (or ResizeInactive) messages to each
+            // pipeline in the frame tree.
+            let pipeline_id = frame.pipeline_id;
+            let pipeline = match self.pipelines.get(&pipeline_id) {
+                None => return warn!("Pipeline {:?} resized after closing.", pipeline_id),
+                Some(pipeline) => pipeline,
+            };
+            let _ = pipeline.event_loop.send(ConstellationControlMsg::Resize(
+                pipeline.id,
+                new_size,
+                size_type
+            ));
+            let pipelines = frame.prev.iter().chain(frame.next.iter())
+                .filter_map(|entry| entry.pipeline_id)
+                .filter_map(|pipeline_id| self.pipelines.get(&pipeline_id));
+            for pipeline in pipelines {
+                let _ = pipeline.event_loop.send(ConstellationControlMsg::ResizeInactive(
+                    pipeline.id,
+                    new_size
+                ));
+            }
+        }
+
+        // Send resize message to any pending pipelines that aren't loaded yet.
+        for pending_frame in &self.pending_frames {
+            let pipeline_id = pending_frame.new_pipeline_id;
+            let pipeline = match self.pipelines.get(&pipeline_id) {
+                None => { warn!("Pending pipeline {:?} is closed", pipeline_id); continue; }
+                Some(pipeline) => pipeline,
+            };
+            if pipeline.frame_id == frame_id {
+                let _ = pipeline.event_loop.send(ConstellationControlMsg::Resize(
+                    pipeline.id,
+                    new_size,
+                    size_type
+                ));
+            }
+        }
+    }
+
     fn clear_joint_session_future(&mut self, frame_id: FrameId) {
         let frame_ids: Vec<FrameId> = self.full_frame_tree_iter(frame_id)
             .map(|frame| frame.id)
@@ -2652,7 +2677,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             self.pipelines.get(&frame.pipeline_id).map(|pipeline: &Pipeline| {
                 let mut frame_tree = SendableFrameTree {
                     pipeline: pipeline.to_sendable(),
-                    size: pipeline.size,
+                    size: frame.size,
                     children: vec!(),
                 };
 

components/constellation/frame.rs

@@ -2,6 +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 euclid::size::TypedSize2D;
 use msg::constellation_msg::{FrameId, PipelineId};
 use pipeline::Pipeline;
 use script_traits::LoadData;
@@ -9,6 +10,7 @@ use std::collections::HashMap;
 use std::iter::once;
 use std::mem::replace;
 use std::time::Instant;
+use style_traits::CSSPixel;
 
 /// A frame in the frame tree.
 /// Each frame is the constellation's view of a browsing context.
@@ -22,13 +24,16 @@ pub struct Frame {
     /// The frame id.
     pub id: FrameId,
 
-    /// The timestamp for the current session history entry
+    /// The size of the frame.
+    pub size: Option<TypedSize2D<f32, CSSPixel>>,
+
+    /// The timestamp for the current session history entry.
     pub instant: Instant,
 
-    /// The pipeline for the current session history entry
+    /// The pipeline for the current session history entry.
     pub pipeline_id: PipelineId,
 
-    /// The load data for the current session history entry
+    /// The load data for the current session history entry.
     pub load_data: LoadData,
 
     /// The past session history, ordered chronologically.
@@ -44,6 +49,7 @@ impl Frame {
     pub fn new(id: FrameId, pipeline_id: PipelineId, load_data: LoadData) -> Frame {
         Frame {
             id: id,
+            size: None,
             pipeline_id: pipeline_id,
             instant: Instant::now(),
             load_data: load_data,

components/constellation/pipeline.rs

@@ -76,10 +76,6 @@ pub struct Pipeline {
     /// The title of the most recently-loaded page.
     pub title: Option<String>,
 
-    /// The size of the frame.
-    /// TODO: move this field to `Frame`.
-    pub size: Option<TypedSize2D<f32, CSSPixel>>,
-
     /// Whether this pipeline is currently running animations. Pipelines that are running
     /// animations cause composites to be continually scheduled.
     pub running_animations: bool,
@@ -291,7 +287,6 @@ impl Pipeline {
                          state.compositor_proxy,
                          state.is_private,
                          url,
-                         state.window_size,
                          state.prev_visibility.unwrap_or(true)))
     }
 
@@ -305,7 +300,6 @@ impl Pipeline {
                compositor_proxy: Box<CompositorProxy + 'static + Send>,
                is_private: bool,
                url: ServoUrl,
-               size: Option<TypedSize2D<f32, CSSPixel>>,
                visible: bool)
                -> Pipeline {
         let pipeline = Pipeline {
@@ -318,7 +312,6 @@ impl Pipeline {
             url: url,
             title: None,
             children: vec!(),
-            size: size,
             running_animations: false,
             visible: visible,
             is_private: is_private,

components/layout/display_list_builder.rs

@@ -34,7 +34,7 @@ use inline::{FIRST_FRAGMENT_OF_ELEMENT, InlineFlow, LAST_FRAGMENT_OF_ELEMENT};
 use ipc_channel::ipc;
 use list_item::ListItemFlow;
 use model::{self, MaybeAuto, specified};
-use msg::constellation_msg::PipelineId;
+use msg::constellation_msg::FrameId;
 use net_traits::image::base::PixelFormat;
 use net_traits::image_cache::UsePlaceholder;
 use range::Range;
@@ -173,7 +173,7 @@ pub struct DisplayListBuildState<'a> {
 
     /// Vector containing iframe sizes, used to inform the constellation about
     /// new iframe sizes
-    pub iframe_sizes: Vec<(PipelineId, TypedSize2D<f32, CSSPixel>)>,
+    pub iframe_sizes: Vec<(FrameId, TypedSize2D<f32, CSSPixel>)>,
 
     /// A stack of clips used to cull display list entries that are outside the
     /// rendered region.
@@ -1809,7 +1809,7 @@ impl FragmentDisplayListBuilding for Fragment {
 
                     let size = Size2D::new(item.bounds().size.width.to_f32_px(),
                                            item.bounds().size.height.to_f32_px());
-                    state.iframe_sizes.push((fragment_info.pipeline_id, TypedSize2D::from_untyped(&size)));
+                    state.iframe_sizes.push((fragment_info.frame_id, TypedSize2D::from_untyped(&size)));
 
                     state.add_display_item(item);
                 }

components/layout/fragment.rs

@@ -26,7 +26,7 @@ use ipc_channel::ipc::IpcSender;
 use layout_debug;
 use model::{self, IntrinsicISizes, IntrinsicISizesContribution, MaybeAuto, SizeConstraint};
 use model::{style_length, ToGfxMatrix};
-use msg::constellation_msg::PipelineId;
+use msg::constellation_msg::{FrameId, PipelineId};
 use net_traits::image::base::{Image, ImageMetadata};
 use net_traits::image_cache::{ImageOrMetadataAvailable, UsePlaceholder};
 use range::*;
@@ -467,10 +467,12 @@ impl ImageFragmentInfo {
     }
 }
 
-/// A fragment that represents an inline frame (iframe). This stores the pipeline ID so that the
+/// A fragment that represents an inline frame (iframe). This stores the frame ID so that the
 /// size of this iframe can be communicated via the constellation to the iframe's own layout thread.
 #[derive(Clone)]
 pub struct IframeFragmentInfo {
+    /// The frame ID of this iframe.
+    pub frame_id: FrameId,
     /// The pipelineID of this iframe.
     pub pipeline_id: PipelineId,
 }
@@ -478,8 +480,10 @@ pub struct IframeFragmentInfo {
 impl IframeFragmentInfo {
     /// Creates the information specific to an iframe fragment.
     pub fn new<N: ThreadSafeLayoutNode>(node: &N) -> IframeFragmentInfo {
+        let frame_id = node.iframe_frame_id();
         let pipeline_id = node.iframe_pipeline_id();
         IframeFragmentInfo {
+            frame_id: frame_id,
             pipeline_id: pipeline_id,
         }
     }

components/msg/constellation_msg.rs

@@ -310,3 +310,4 @@ pub enum FrameType {
     IFrame,
     MozBrowserIFrame,
 }
+

components/script/dom/htmlformelement.rs

@@ -345,7 +345,7 @@ impl HTMLFormElement {
         let _target = submitter.target();
         // TODO: Handle browsing contexts, partially loaded documents (step 16-17)
 
-        let mut load_data = LoadData::new(action_components, doc.get_referrer_policy(), Some(doc.url()));
+        let mut load_data = LoadData::new(action_components, None, doc.get_referrer_policy(), Some(doc.url()));
 
         // Step 18
         match (&*scheme, method) {

components/script/dom/htmliframeelement.rs

@@ -44,7 +44,7 @@ use msg::constellation_msg::{FrameType, FrameId, PipelineId, TraversalDirection}
 use net_traits::response::HttpsState;
 use script_layout_interface::message::ReflowQueryType;
 use script_thread::{ScriptThread, Runnable};
-use script_traits::{IFrameLoadInfo, IFrameLoadInfoWithData, LoadData};
+use script_traits::{IFrameLoadInfo, IFrameLoadInfoWithData, LoadData, UpdatePipelineIdReason};
 use script_traits::{MozBrowserEvent, NewLayoutInfo, ScriptMsg as ConstellationMsg};
 use script_traits::IFrameSandboxState::{IFrameSandboxed, IFrameUnsandboxed};
 use servo_atoms::Atom;
@@ -69,6 +69,12 @@ bitflags! {
     }
 }
 
+#[derive(PartialEq)]
+pub enum NavigationType {
+    InitialAboutBlank,
+    Regular,
+}
+
 #[derive(PartialEq)]
 enum ProcessingMode {
     FirstTime,
@@ -80,6 +86,7 @@ pub struct HTMLIFrameElement {
     htmlelement: HTMLElement,
     frame_id: FrameId,
     pipeline_id: Cell<Option<PipelineId>>,
+    pending_pipeline_id: Cell<Option<PipelineId>>,
     sandbox: MutNullableJS<DOMTokenList>,
     sandbox_allowance: Cell<Option<SandboxAllowance>>,
     load_blocker: DOMRefCell<Option<LoadBlocker>>,
@@ -108,12 +115,14 @@ impl HTMLIFrameElement {
     pub fn generate_new_pipeline_id(&self) -> (Option<PipelineId>, PipelineId) {
         let old_pipeline_id = self.pipeline_id.get();
         let new_pipeline_id = PipelineId::new();
-        self.pipeline_id.set(Some(new_pipeline_id));
         debug!("Frame {} created pipeline {}.", self.frame_id, new_pipeline_id);
         (old_pipeline_id, new_pipeline_id)
     }
 
-    pub fn navigate_or_reload_child_browsing_context(&self, load_data: Option<LoadData>, replace: bool) {
+    pub fn navigate_or_reload_child_browsing_context(&self,
+                                                     load_data: Option<LoadData>,
+                                                     nav_type: NavigationType,
+                                                     replace: bool) {
         let sandboxed = if self.is_sandboxed() {
             IFrameSandboxed
         } else {
@@ -136,6 +145,7 @@ impl HTMLIFrameElement {
 
         let window = window_from_node(self);
         let (old_pipeline_id, new_pipeline_id) = self.generate_new_pipeline_id();
+        self.pending_pipeline_id.set(Some(new_pipeline_id));
         let private_iframe = self.privatebrowsing();
         let frame_type = if self.Mozbrowser() { FrameType::MozBrowserIFrame } else { FrameType::IFrame };
 
@@ -149,12 +159,13 @@ impl HTMLIFrameElement {
             replace: replace,
         };
 
-        if load_data.as_ref().map_or(false, |d| d.url.as_str() == "about:blank") {
+        match nav_type {
+            NavigationType::InitialAboutBlank => {
                 let (pipeline_sender, pipeline_receiver) = ipc::channel().unwrap();
 
                 global_scope
                     .constellation_chan()
-                  .send(ConstellationMsg::ScriptLoadedAboutBlankInIFrame(load_info, pipeline_sender))
+                    .send(ConstellationMsg::ScriptNewIFrame(load_info, pipeline_sender))
                     .unwrap();
 
                 let new_layout_info = NewLayoutInfo {
@@ -168,8 +179,10 @@ impl HTMLIFrameElement {
                     layout_threads: PREFS.get("layout.threads").as_u64().expect("count") as usize,
                 };
 
+                self.pipeline_id.set(Some(new_pipeline_id));
                 ScriptThread::process_attach_layout(new_layout_info, document.origin().clone());
-        } else {
+            },
+            NavigationType::Regular => {
                 let load_info = IFrameLoadInfoWithData {
                     info: load_info,
                     load_data: load_data,
@@ -181,6 +194,7 @@ impl HTMLIFrameElement {
                   .send(ConstellationMsg::ScriptLoadedURLInIFrame(load_info))
                   .unwrap();
             }
+        }
 
         if PREFS.is_mozbrowser_enabled() {
             // https://developer.mozilla.org/en-US/docs/Web/Events/mozbrowserloadstart
@@ -192,9 +206,10 @@ impl HTMLIFrameElement {
     fn process_the_iframe_attributes(&self, mode: ProcessingMode) {
         // TODO: srcdoc
 
+        let window = window_from_node(self);
+
         // https://github.com/whatwg/html/issues/490
         if mode == ProcessingMode::FirstTime && !self.upcast::<Element>().has_attribute(&local_name!("src")) {
-            let window = window_from_node(self);
             let event_loop = window.dom_manipulation_task_source();
             let _ = event_loop.queue(box IFrameLoadEventSteps::new(self),
                                      window.upcast());
@@ -205,9 +220,15 @@ impl HTMLIFrameElement {
 
         // TODO: check ancestor browsing contexts for same URL
 
+        let creator_pipeline_id = if url.as_str() == "about:blank" {
+            Some(window.upcast::<GlobalScope>().pipeline_id())
+        } else {
+            None
+        };
+
         let document = document_from_node(self);
-        self.navigate_or_reload_child_browsing_context(
+        let load_data = LoadData::new(url, creator_pipeline_id, document.get_referrer_policy(), Some(document.url()));
-            Some(LoadData::new(url, document.get_referrer_policy(), Some(document.url()))), false);
+        self.navigate_or_reload_child_browsing_context(Some(load_data), NavigationType::Regular, false);
     }
 
     #[allow(unsafe_code)]
@@ -225,19 +246,30 @@ impl HTMLIFrameElement {
         // Synchronously create a new context and navigate it to about:blank.
         let url = ServoUrl::parse("about:blank").unwrap();
         let document = document_from_node(self);
-        let load_data = LoadData::new(url,
+        let pipeline_id = Some(window_from_node(self).upcast::<GlobalScope>().pipeline_id());
-                                      document.get_referrer_policy(),
+        let load_data = LoadData::new(url, pipeline_id, document.get_referrer_policy(), Some(document.url().clone()));
-                                      Some(document.url().clone()));
+        self.navigate_or_reload_child_browsing_context(Some(load_data), NavigationType::InitialAboutBlank, false);
-        self.navigate_or_reload_child_browsing_context(Some(load_data), false);
+    }
+
+    pub fn update_pipeline_id(&self, new_pipeline_id: PipelineId, reason: UpdatePipelineIdReason) {
+        if self.pending_pipeline_id.get() != Some(new_pipeline_id) && reason == UpdatePipelineIdReason::Navigation {
+            return;
         }
 
-    pub fn update_pipeline_id(&self, new_pipeline_id: PipelineId) {
         self.pipeline_id.set(Some(new_pipeline_id));
 
+        // Only terminate the load blocker if the pipeline id was updated due to a traversal.
+        // The load blocker will be terminated for a navigation in iframe_load_event_steps.
+        if reason == UpdatePipelineIdReason::Traversal {
             let mut blocker = self.load_blocker.borrow_mut();
             LoadBlocker::terminate(&mut blocker);
+        }
 
         self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
+        let window = window_from_node(self);
+        window.reflow(ReflowGoal::ForDisplay,
+                      ReflowQueryType::NoQuery,
+                      ReflowReason::FramedContentChanged);
     }
 
     fn new_inherited(local_name: LocalName,
@@ -247,6 +279,7 @@ impl HTMLIFrameElement {
             htmlelement: HTMLElement::new_inherited(local_name, prefix, document),
             frame_id: FrameId::new(),
             pipeline_id: Cell::new(None),
+            pending_pipeline_id: Cell::new(None),
             sandbox: Default::default(),
             sandbox_allowance: Cell::new(None),
             load_blocker: DOMRefCell::new(None),
@@ -296,7 +329,7 @@ impl HTMLIFrameElement {
     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().
-        if Some(loaded_pipeline) != self.pipeline_id() { return; }
+        if Some(loaded_pipeline) != self.pending_pipeline_id.get() { return; }
 
         // TODO A cross-origin child document would not be easily accessible
         //      from this script thread. It's unclear how to implement
@@ -330,7 +363,8 @@ impl HTMLIFrameElement {
 }
 
 pub trait HTMLIFrameElementLayoutMethods {
-    fn pipeline_id(self) -> Option<PipelineId>;
+    fn pipeline_id(&self) -> Option<PipelineId>;
+    fn frame_id(&self) -> FrameId;
     fn get_width(&self) -> LengthOrPercentageOrAuto;
     fn get_height(&self) -> LengthOrPercentageOrAuto;
 }
@@ -338,12 +372,21 @@ pub trait HTMLIFrameElementLayoutMethods {
 impl HTMLIFrameElementLayoutMethods for LayoutJS<HTMLIFrameElement> {
     #[inline]
     #[allow(unsafe_code)]
-    fn pipeline_id(self) -> Option<PipelineId> {
+    fn pipeline_id(&self) -> Option<PipelineId> {
         unsafe {
             (*self.unsafe_get()).pipeline_id.get()
         }
     }
 
+    #[inline]
+    #[allow(unsafe_code)]
+    fn frame_id(&self) -> FrameId {
+        unsafe {
+            (*self.unsafe_get()).frame_id
+        }
+    }
+
+
     #[allow(unsafe_code)]
     fn get_width(&self) -> LengthOrPercentageOrAuto {
         unsafe {
@@ -563,7 +606,7 @@ impl HTMLIFrameElementMethods for HTMLIFrameElement {
     fn Reload(&self, _hard_reload: bool) -> ErrorResult {
         if self.Mozbrowser() {
             if self.upcast::<Node>().is_in_doc_with_browsing_context() {
-                self.navigate_or_reload_child_browsing_context(None, true);
+                self.navigate_or_reload_child_browsing_context(None, NavigationType::Regular, true);
             }
             Ok(())
         } else {
@@ -739,6 +782,7 @@ impl VirtualMethods for HTMLIFrameElement {
         // a new iframe. Without this, the constellation gets very
         // confused.
         self.pipeline_id.set(None);
+        self.pending_pipeline_id.set(None);
     }
 }
 

components/script/dom/node.rs

@@ -61,7 +61,7 @@ use heapsize::{HeapSizeOf, heap_size_of};
 use html5ever::{Prefix, Namespace, QualName};
 use js::jsapi::{JSContext, JSObject, JSRuntime};
 use libc::{self, c_void, uintptr_t};
-use msg::constellation_msg::PipelineId;
+use msg::constellation_msg::{FrameId, PipelineId};
 use ref_slice::ref_slice;
 use script_layout_interface::{HTMLCanvasData, OpaqueStyleAndLayoutData, SVGSVGData};
 use script_layout_interface::{LayoutElementType, LayoutNodeType, TrustedNodeAddress};
@@ -970,6 +970,7 @@ pub trait LayoutNodeHelpers {
     fn image_url(&self) -> Option<ServoUrl>;
     fn canvas_data(&self) -> Option<HTMLCanvasData>;
     fn svg_data(&self) -> Option<SVGSVGData>;
+    fn iframe_frame_id(&self) -> FrameId;
     fn iframe_pipeline_id(&self) -> PipelineId;
     fn opaque(&self) -> OpaqueNode;
 }
@@ -1120,6 +1121,12 @@ impl LayoutNodeHelpers for LayoutJS<Node> {
             .map(|svg| svg.data())
     }
 
+    fn iframe_frame_id(&self) -> FrameId {
+        let iframe_element = self.downcast::<HTMLIFrameElement>()
+            .expect("not an iframe element!");
+        iframe_element.frame_id()
+    }
+
     fn iframe_pipeline_id(&self) -> PipelineId {
         let iframe_element = self.downcast::<HTMLIFrameElement>()
             .expect("not an iframe element!");

components/script/dom/window.rs

@@ -1537,10 +1537,10 @@ impl Window {
                 }
         }
 
+        let pipeline_id = self.upcast::<GlobalScope>().pipeline_id();
         self.main_thread_script_chan().send(
-            MainThreadScriptMsg::Navigate(self.upcast::<GlobalScope>().pipeline_id(),
+            MainThreadScriptMsg::Navigate(pipeline_id,
-                LoadData::new(url, referrer_policy, Some(doc.url())),
+                LoadData::new(url, Some(pipeline_id), referrer_policy, Some(doc.url())), replace)).unwrap();
-                replace)).unwrap();
     }
 
     pub fn handle_fire_timer(&self, timer_id: TimerEventId) {

components/script/layout_wrapper.rs

@@ -44,7 +44,7 @@ use dom::node::{LayoutNodeHelpers, Node};
 use dom::text::Text;
 use gfx_traits::ByteIndex;
 use html5ever::{LocalName, Namespace};
-use msg::constellation_msg::PipelineId;
+use msg::constellation_msg::{FrameId, PipelineId};
 use range::Range;
 use script_layout_interface::{HTMLCanvasData, LayoutNodeType, SVGSVGData, TrustedNodeAddress};
 use script_layout_interface::{OpaqueStyleAndLayoutData, PartialPersistentLayoutData};
@@ -908,6 +908,11 @@ impl<'ln> ThreadSafeLayoutNode for ServoThreadSafeLayoutNode<'ln> {
         this.svg_data()
     }
 
+    fn iframe_frame_id(&self) -> FrameId {
+        let this = unsafe { self.get_jsmanaged() };
+        this.iframe_frame_id()
+    }
+
     fn iframe_pipeline_id(&self) -> PipelineId {
         let this = unsafe { self.get_jsmanaged() };
         this.iframe_pipeline_id()

components/script/script_thread.rs

@@ -46,7 +46,7 @@ use dom::element::Element;
 use dom::event::{Event, EventBubbles, EventCancelable};
 use dom::globalscope::GlobalScope;
 use dom::htmlanchorelement::HTMLAnchorElement;
-use dom::htmliframeelement::HTMLIFrameElement;
+use dom::htmliframeelement::{HTMLIFrameElement, NavigationType};
 use dom::mutationobserver::MutationObserver;
 use dom::node::{Node, NodeDamage, window_from_node};
 use dom::serviceworker::TrustedServiceWorkerAddress;
@@ -87,7 +87,7 @@ use script_runtime::{ScriptPort, StackRootTLS, get_reports, new_rt_and_cx};
 use script_traits::{CompositorEvent, ConstellationControlMsg};
 use script_traits::{DocumentActivity, DiscardBrowsingContext, EventResult};
 use script_traits::{InitialScriptState, LayoutMsg, LoadData, MouseButton, MouseEventType, MozBrowserEvent};
-use script_traits::{NewLayoutInfo, ScriptMsg as ConstellationMsg};
+use script_traits::{NewLayoutInfo, ScriptMsg as ConstellationMsg, UpdatePipelineIdReason};
 use script_traits::{ScriptThreadFactory, TimerEvent, TimerSchedulerMsg, TimerSource};
 use script_traits::{TouchEventType, TouchId, UntrustedNodeAddress, WindowSizeData, WindowSizeType};
 use script_traits::CompositorEvent::{KeyEvent, MouseButtonEvent, MouseMoveEvent, ResizeEvent};
@@ -555,8 +555,8 @@ impl ScriptThreadFactory for ScriptThread {
             let mut failsafe = ScriptMemoryFailsafe::new(&script_thread);
 
             let origin = MutableOrigin::new(load_data.url.origin());
-            let new_load = InProgressLoad::new(id, frame_id, parent_info, layout_chan, window_size,
+            let new_load = InProgressLoad::new(id, frame_id, parent_info,
-                                               load_data.url.clone(), origin);
+                                               layout_chan, window_size, load_data.url.clone(), origin);
             script_thread.start_page_load(new_load, load_data);
 
             let reporter_name = format!("script-reporter-{}", id);
@@ -827,7 +827,22 @@ impl ScriptThread {
                 FromConstellation(ConstellationControlMsg::AttachLayout(
                         new_layout_info)) => {
                     self.profile_event(ScriptThreadEventCategory::AttachLayout, || {
-                        let origin = MutableOrigin::new(new_layout_info.load_data.url.origin());
+                        // If this is an about:blank load, it must share the creator's origin.
+                        // This must match the logic in the constellation when creating a new pipeline
+                        let origin = if new_layout_info.load_data.url.as_str() != "about:blank" {
+                            MutableOrigin::new(new_layout_info.load_data.url.origin())
+                        } else if let Some(parent) = new_layout_info.parent_info
+                                .and_then(|(pipeline_id, _)| self.documents.borrow()
+                                .find_document(pipeline_id)) {
+                            parent.origin().clone()
+                        } else if let Some(creator) = new_layout_info.load_data.creator_pipeline_id
+                                .and_then(|pipeline_id| self.documents.borrow()
+                                .find_document(pipeline_id)) {
+                            creator.origin().clone()
+                        } else {
+                            MutableOrigin::new(ImmutableOrigin::new_opaque())
+                        };
+
                         self.handle_new_layout(new_layout_info, origin);
                     })
                 }
@@ -1043,10 +1058,12 @@ impl ScriptThread {
                                                  event),
             ConstellationControlMsg::UpdatePipelineId(parent_pipeline_id,
                                                       frame_id,
-                                                      new_pipeline_id) =>
+                                                      new_pipeline_id,
+                                                      reason) =>
                 self.handle_update_pipeline_id(parent_pipeline_id,
                                                frame_id,
-                                               new_pipeline_id),
+                                               new_pipeline_id,
+                                               reason),
             ConstellationControlMsg::FocusIFrame(parent_pipeline_id, frame_id) =>
                 self.handle_focus_iframe_msg(parent_pipeline_id, frame_id),
             ConstellationControlMsg::WebDriverScriptCommand(pipeline_id, msg) =>
@@ -1062,8 +1079,6 @@ impl ScriptThread {
                 self.handle_frame_load_event(parent_id, frame_id, child_id),
             ConstellationControlMsg::DispatchStorageEvent(pipeline_id, storage, url, key, old_value, new_value) =>
                 self.handle_storage_event(pipeline_id, storage, url, key, old_value, new_value),
-            ConstellationControlMsg::FramedContentChanged(parent_pipeline_id, frame_id) =>
-                self.handle_framed_content_changed(parent_pipeline_id, frame_id),
             ConstellationControlMsg::ReportCSSError(pipeline_id, filename, line, column, msg) =>
                 self.handle_css_error_reporting(pipeline_id, filename, line, column, msg),
             ConstellationControlMsg::Reload(pipeline_id) =>
@@ -1399,20 +1414,6 @@ impl ScriptThread {
         }
     }
 
-    fn handle_framed_content_changed(&self,
-                                     parent_pipeline_id: PipelineId,
-                                     frame_id: FrameId) {
-        let doc = self.documents.borrow().find_document(parent_pipeline_id).unwrap();
-        let frame_element = doc.find_iframe(frame_id);
-        if let Some(ref frame_element) = frame_element {
-            frame_element.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
-            let window = doc.window();
-            window.reflow(ReflowGoal::ForDisplay,
-                          ReflowQueryType::NoQuery,
-                          ReflowReason::FramedContentChanged);
-        }
-    }
-
     fn handle_post_message_msg(&self, pipeline_id: PipelineId, origin: Option<ImmutableOrigin>, data: Vec<u8>) {
         match { self.documents.borrow().find_window(pipeline_id) } {
             None => return warn!("postMessage after pipeline {} closed.", pipeline_id),
@@ -1443,10 +1444,11 @@ impl ScriptThread {
     fn handle_update_pipeline_id(&self,
                                  parent_pipeline_id: PipelineId,
                                  frame_id: FrameId,
-                                 new_pipeline_id: PipelineId) {
+                                 new_pipeline_id: PipelineId,
+                                 reason: UpdatePipelineIdReason) {
         let frame_element = self.documents.borrow().find_iframe(parent_pipeline_id, frame_id);
         if let Some(frame_element) = frame_element {
-            frame_element.update_pipeline_id(new_pipeline_id);
+            frame_element.update_pipeline_id(new_pipeline_id, reason);
         }
     }
 
@@ -2065,7 +2067,7 @@ impl ScriptThread {
             Some(frame_id) => {
                 let iframe = self.documents.borrow().find_iframe(parent_pipeline_id, frame_id);
                 if let Some(iframe) = iframe {
-                    iframe.navigate_or_reload_child_browsing_context(Some(load_data), replace);
+                    iframe.navigate_or_reload_child_browsing_context(Some(load_data), NavigationType::Regular, replace);
                 }
             }
             None => {

components/script_layout_interface/wrapper_traits.rs

@@ -11,7 +11,7 @@ use SVGSVGData;
 use atomic_refcell::AtomicRefCell;
 use gfx_traits::{ByteIndex, FragmentType, combine_id_with_fragment_type};
 use html5ever::{Namespace, LocalName};
-use msg::constellation_msg::PipelineId;
+use msg::constellation_msg::{FrameId, PipelineId};
 use range::Range;
 use servo_url::ServoUrl;
 use std::fmt::Debug;
@@ -271,6 +271,10 @@ pub trait ThreadSafeLayoutNode: Clone + Copy + Debug + GetLayoutData + NodeInfo
 
     fn svg_data(&self) -> Option<SVGSVGData>;
 
+    /// If this node is an iframe element, returns its frame ID. If this node is
+    /// not an iframe element, fails.
+    fn iframe_frame_id(&self) -> FrameId;
+
     /// If this node is an iframe element, returns its pipeline ID. If this node is
     /// not an iframe element, fails.
     fn iframe_pipeline_id(&self) -> PipelineId;

components/script_traits/lib.rs

@@ -134,6 +134,8 @@ pub enum LayoutControlMsg {
 pub struct LoadData {
     /// The URL.
     pub url: ServoUrl,
+    /// The creator pipeline id if this is an about:blank load.
+    pub creator_pipeline_id: Option<PipelineId>,
     /// The method.
     #[serde(deserialize_with = "::hyper_serde::deserialize",
             serialize_with = "::hyper_serde::serialize")]
@@ -152,9 +154,14 @@ pub struct LoadData {
 
 impl LoadData {
     /// Create a new `LoadData` object.
-    pub fn new(url: ServoUrl, referrer_policy: Option<ReferrerPolicy>, referrer_url: Option<ServoUrl>) -> LoadData {
+    pub fn new(url: ServoUrl,
+               creator_pipeline_id: Option<PipelineId>,
+               referrer_policy: Option<ReferrerPolicy>,
+               referrer_url: Option<ServoUrl>)
+               -> LoadData {
         LoadData {
             url: url,
+            creator_pipeline_id: creator_pipeline_id,
             method: Method::Get,
             headers: Headers::new(),
             data: None,
@@ -211,6 +218,15 @@ pub enum DocumentActivity {
     FullyActive,
 }
 
+/// The reason why the pipeline id of an iframe is being updated.
+#[derive(Copy, Clone, PartialEq, Eq, Hash, HeapSizeOf, Debug, Deserialize, Serialize)]
+pub enum UpdatePipelineIdReason {
+    /// The pipeline id is being updated due to a navigation.
+    Navigation,
+    /// The pipeline id is being updated due to a history traversal.
+    Traversal,
+}
+
 /// Messages sent from the constellation or layout to the script thread.
 #[derive(Deserialize, Serialize)]
 pub enum ConstellationControlMsg {
@@ -249,7 +265,7 @@ pub enum ConstellationControlMsg {
     MozBrowserEvent(PipelineId, Option<FrameId>, MozBrowserEvent),
     /// Updates the current pipeline ID of a given iframe.
     /// First PipelineId is for the parent, second is the new PipelineId for the frame.
-    UpdatePipelineId(PipelineId, FrameId, PipelineId),
+    UpdatePipelineId(PipelineId, FrameId, PipelineId, UpdatePipelineIdReason),
     /// Set an iframe to be focused. Used when an element in an iframe gains focus.
     /// PipelineId is for the parent, FrameId is for the actual frame.
     FocusIFrame(PipelineId, FrameId),
@@ -274,9 +290,6 @@ pub enum ConstellationControlMsg {
     /// Cause a `storage` event to be dispatched at the appropriate window.
     /// The strings are key, old value and new value.
     DispatchStorageEvent(PipelineId, StorageType, ServoUrl, Option<String>, Option<String>, Option<String>),
-    /// Notifies a parent pipeline that one of its child frames is now active.
-    /// PipelineId is for the parent, FrameId is the child frame.
-    FramedContentChanged(PipelineId, FrameId),
     /// Report an error from a CSS parser for the given pipeline
     ReportCSSError(PipelineId, String, usize, usize, String),
     /// Reload the given page.
@@ -312,7 +325,6 @@ impl fmt::Debug for ConstellationControlMsg {
             WebFontLoaded(..) => "WebFontLoaded",
             DispatchFrameLoadEvent { .. } => "DispatchFrameLoadEvent",
             DispatchStorageEvent(..) => "DispatchStorageEvent",
-            FramedContentChanged(..) => "FramedContentChanged",
             ReportCSSError(..) => "ReportCSSError",
             Reload(..) => "Reload",
             WebVREvents(..) => "WebVREvents",

components/script_traits/script_msg.rs

@@ -34,8 +34,8 @@ use webrender_traits::ClipId;
 pub enum LayoutMsg {
     /// Indicates whether this pipeline is currently running animations.
     ChangeRunningAnimationsState(PipelineId, AnimationState),
-    /// Inform the constellation of the size of the pipeline's viewport.
+    /// Inform the constellation of the size of the frame's viewport.
-    FrameSizes(Vec<(PipelineId, TypedSize2D<f32, CSSPixel>)>),
+    FrameSizes(Vec<(FrameId, TypedSize2D<f32, CSSPixel>)>),
     /// Requests that the constellation inform the compositor of the a cursor change.
     SetCursor(Cursor),
     /// Notifies the constellation that the viewport has been constrained in some manner
@@ -120,8 +120,8 @@ pub enum ScriptMsg {
     VisibilityChangeComplete(PipelineId, bool),
     /// A load has been requested in an IFrame.
     ScriptLoadedURLInIFrame(IFrameLoadInfoWithData),
-    /// A load of `about:blank` has been completed in an IFrame.
+    /// A load of the initial `about:blank` has been completed in an IFrame.
-    ScriptLoadedAboutBlankInIFrame(IFrameLoadInfo, IpcSender<LayoutControlMsg>),
+    ScriptNewIFrame(IFrameLoadInfo, IpcSender<LayoutControlMsg>),
     /// Requests that the constellation set the contents of the clipboard
     SetClipboardContents(String),
     /// Mark a new document as active

components/webdriver_server/lib.rs

@@ -357,7 +357,7 @@ impl Handler {
 
         let (sender, receiver) = ipc::channel().unwrap();
 
-        let load_data = LoadData::new(url, None, None);
+        let load_data = LoadData::new(url, Some(pipeline_id), None, None);
         let cmd_msg = WebDriverCommandMsg::LoadUrl(pipeline_id, load_data, sender.clone());
         self.constellation_chan.send(ConstellationMsg::WebDriverCommand(cmd_msg)).unwrap();
 

tests/wpt/metadata/MANIFEST.json

@@ -331418,6 +331418,12 @@
      {}
     ]
    ],
+   "html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html": [
+    [
+     "/html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html",
+     {}
+    ]
+   ],
    "html/semantics/embedded-content/the-iframe-element/cross_origin_parentage.html": [
     [
      "/html/semantics/embedded-content/the-iframe-element/cross_origin_parentage.html",
@@ -570683,6 +570689,10 @@
    "56df0cb79a1af927a0209c0bbbb5edb25ccaee5f",
    "testharness"
   ],
+  "html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html": [
+   "46708fc218e559fba7049a36888a7c8a24c22672",
+   "testharness"
+  ],
   "html/semantics/embedded-content/the-iframe-element/cross_origin_child.html": [
    "a42082bb612b280eda5aa598ed750cfce3edd537",
    "support"

tests/wpt/mozilla/meta/css/matchMedia.html.ini

@@ -1,4 +1,5 @@
 [matchMedia.html]
+  disabled: true
   type: testharness
   [window.matchMedia exists]
     expected: FAIL

tests/wpt/web-platform-tests/html/semantics/embedded-content/the-iframe-element/content_document_changes_only_after_load_matures.html

@@ -0,0 +1,21 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>Iframe's contentDocument should only change after its pending load has matured.</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<body></body>
+<script>
+async_test(function(t) {
+    var iframe = document.createElement("iframe");
+    document.body.appendChild(iframe);
+    iframe.onload = t.step_func(function() {
+        assert_true(iframe.contentDocument.location.toString().includes("support/blank.htm"));
+        t.done();
+    });
+
+    assert_equals(iframe.contentDocument.location.toString(), "about:blank");
+    iframe.src = "support/blank.htm?pipe=trickle(d2)";
+    // The location of the contentDocument should not change until the new document has matured.
+    assert_equals(iframe.contentDocument.location.toString(), "about:blank");
+}, "contentDocument should only change after a load matures.");
+</script>