Add empty handler for CanvasFontQuery

components/layout/query.rs

@@ -90,6 +90,9 @@ pub struct LayoutThreadData {
 
     /// A queued response for the viewport dimensions for a given browsing context.
     pub inner_window_dimensions_response: Option<TypedSize2D<f32, CSSPixel>>,
+
+    /// A queued response for the resolved font property of a canvas element.
+    pub canvas_font_response: String,
 }
 
 pub struct LayoutRPCImpl(pub Arc<Mutex<LayoutThreadData>>);
@@ -1095,3 +1098,11 @@ fn is_last_table_row() -> bool {
     // FIXME(ferjm) Implement this.
     false
 }
+
+pub fn process_canvas_font_request<'dom>(
+    _node: impl LayoutNode<'dom>,
+    _font: &str,
+    _layout_root: &mut dyn Flow,
+) -> String {
+    unimplemented!()
+}

components/layout_thread/lib.rs

@@ -50,12 +50,14 @@ use layout::flow_ref::FlowRef;
 use layout::incremental::{RelayoutMode, SpecialRestyleDamage};
 use layout::layout_debug;
 use layout::parallel;
+use layout::query::{
+    process_canvas_font_request, process_offset_parent_query, process_resolved_style_request,
+};
 use layout::query::{process_client_rect_query, process_element_inner_text_query};
 use layout::query::{
     process_content_box_request, process_content_boxes_request, LayoutRPCImpl, LayoutThreadData,
 };
 use layout::query::{process_node_scroll_area_request, process_node_scroll_id_request};
-use layout::query::{process_offset_parent_query, process_resolved_style_request};
 use layout::sequential;
 use layout::traversal::{
     ComputeStackingRelativePositions, PreorderFlowTraversal, RecalcStyleAndConstructFlows,
@@ -575,6 +577,7 @@ impl LayoutThread {
                 nodes_from_point_response: vec![],
                 element_inner_text_response: String::new(),
                 inner_window_dimensions_response: None,
+                canvas_font_response: String::new(),
             })),
             webrender_image_cache: Arc::new(RwLock::new(FnvHashMap::default())),
             paint_time_metrics: paint_time_metrics,
@@ -1600,8 +1603,10 @@ impl LayoutThread {
                         .get(&browsing_context_id)
                         .cloned();
                 },
-                &QueryMsg::CanvasFontQuery(_node, ref _font) => {
-                    unimplemented!();
+                &QueryMsg::CanvasFontQuery(node, ref font) => {
+                    let node = unsafe { ServoLayoutNode::new(&node) };
+                    rw_data.canvas_font_response =
+                        process_canvas_font_request(node, font, root_flow);
                 },
             },
             ReflowGoal::Full | ReflowGoal::TickAnimations => {},

components/script_layout_interface/message.rs

@@ -107,7 +107,6 @@ pub enum QueryMsg {
     OffsetParentQuery(OpaqueNode),
     TextIndexQuery(OpaqueNode, Point2D<f32>),
     NodesFromPointQuery(Point2D<f32>, NodesFromPointQueryType),
-    CanvasFontQuery(OpaqueNode, String),
 
     // FIXME(nox): The following queries use the TrustedNodeAddress to
     // access actual DOM nodes, but those values can be constructed from
@@ -117,6 +116,7 @@ pub enum QueryMsg {
     StyleQuery,
     ElementInnerTextQuery(TrustedNodeAddress),
     InnerWindowDimensionsQuery(BrowsingContextId),
+    CanvasFontQuery(TrustedNodeAddress, String),
 }
 
 /// Any query to perform with this reflow.