script: Manage <iframe> sizes in Window (#34643)

Manage `<iframe>` size updates in `Window`. In addition to removing
duplicated code, this will allow setting `<iframe>` sizes synchronously
on child `Pipeline`s of the same origin in the script process in a
followup change. The goal is remove flakiness from `<iframe>` sizing.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

components/shared/script/script_msg.rs

@@ -46,8 +46,6 @@ pub struct IFrameSizeMsg {
 /// Messages from the layout to the constellation.
 #[derive(Deserialize, Serialize)]
 pub enum LayoutMsg {
-    /// Inform the constellation of the size of the iframe's viewport.
-    IFrameSizes(Vec<IFrameSizeMsg>),
     /// Requests that the constellation inform the compositor that it needs to record
     /// the time when the frame with the given ID (epoch) is painted.
     PendingPaintMetric(PipelineId, Epoch),
@@ -57,7 +55,6 @@ impl fmt::Debug for LayoutMsg {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         use self::LayoutMsg::*;
         let variant = match *self {
-            IFrameSizes(..) => "IFrameSizes",
             PendingPaintMetric(..) => "PendingPaintMetric",
         };
         write!(formatter, "LayoutMsg::{}", variant)
@@ -260,6 +257,8 @@ pub enum ScriptMsg {
     GetWebGPUChan(IpcSender<Option<WebGPU>>),
     /// Notify the constellation of a pipeline's document's title.
     TitleChanged(PipelineId, String),
+    /// Notify the constellation that the size of some `<iframe>`s has changed.
+    IFrameSizes(Vec<IFrameSizeMsg>),
 }
 
 impl fmt::Debug for ScriptMsg {
@@ -320,6 +319,7 @@ impl fmt::Debug for ScriptMsg {
             #[cfg(feature = "webgpu")]
             GetWebGPUChan(..) => "GetWebGPUChan",
             TitleChanged(..) => "TitleChanged",
+            IFrameSizes(..) => "IFramSizes",
         };
         write!(formatter, "ScriptMsg::{}", variant)
     }

components/shared/script_layout/Cargo.toml

@@ -18,6 +18,7 @@ atomic_refcell = { workspace = true }
 canvas_traits = { workspace = true }
 crossbeam-channel = { workspace = true }
 euclid = { workspace = true }
+fnv = { workspace = true }
 fonts = { path = "../../fonts" }
 fonts_traits = { workspace = true }
 html5ever = { workspace = true }

components/shared/script_layout/lib.rs

@@ -23,6 +23,7 @@ use base::Epoch;
 use canvas_traits::canvas::{CanvasId, CanvasMsg};
 use euclid::default::{Point2D, Rect};
 use euclid::Size2D;
+use fnv::FnvHashMap;
 use fonts::SystemFontServiceProxy;
 use ipc_channel::ipc::IpcSender;
 use libc::c_void;
@@ -257,10 +258,6 @@ pub trait Layout {
     fn query_content_boxes(&self, node: OpaqueNode) -> Vec<Rect<Au>>;
     fn query_client_rect(&self, node: OpaqueNode) -> Rect<i32>;
     fn query_element_inner_outer_text(&self, node: TrustedNodeAddress) -> String;
-    fn query_inner_window_dimension(
-        &self,
-        context: BrowsingContextId,
-    ) -> Option<Size2D<f32, CSSPixel>>;
     fn query_nodes_from_point(
         &self,
         point: Point2D<f32>,
@@ -400,11 +397,24 @@ pub struct Reflow {
     pub page_clip_rect: Rect<Au>,
 }
 
+#[derive(Clone, Debug, MallocSizeOf)]
+pub struct IFrameSize {
+    pub browsing_context_id: BrowsingContextId,
+    pub pipeline_id: PipelineId,
+    pub size: Size2D<f32, CSSPixel>,
+}
+
+pub type IFrameSizes = FnvHashMap<BrowsingContextId, IFrameSize>;
+
 /// Information derived from a layout pass that needs to be returned to the script thread.
 #[derive(Debug, Default)]
 pub struct ReflowResult {
     /// The list of images that were encountered that are in progress.
     pub pending_images: Vec<PendingImage>,
+    /// The list of iframes in this layout and their sizes, used in order
+    /// to communicate them with the Constellation and also the `Window`
+    /// element of their content pages.
+    pub iframe_sizes: IFrameSizes,
 }
 
 /// Information needed for a script-initiated reflow.