Share script threads per-tab and per-eTLD+1.

components/script_traits/lib.rs

@@ -162,19 +162,20 @@ impl LoadData {
     }
 }
 
-/// The initial data associated with a newly-created framed pipeline.
+/// The initial data required to create a new layout attached to an existing script thread.
 #[derive(Deserialize, Serialize)]
 pub struct NewLayoutInfo {
-    /// Id of the parent of this new pipeline.
-    pub parent_pipeline_id: PipelineId,
+    /// The ID of the parent pipeline and frame type, if any.
+    /// If `None`, this is a root pipeline.
+    pub parent_info: Option<(PipelineId, FrameType)>,
     /// Id of the newly-created pipeline.
     pub new_pipeline_id: PipelineId,
     /// Id of the frame associated with this pipeline.
     pub frame_id: FrameId,
-    /// Type of the frame associated with this pipeline.
-    pub frame_type: FrameType,
     /// Network request data which will be initiated by the script thread.
     pub load_data: LoadData,
+    /// Information about the initial window size.
+    pub window_size: Option<WindowSizeData>,
     /// A port on which layout can receive messages from the pipeline.
     pub pipeline_port: IpcReceiver<LayoutControlMsg>,
     /// A sender for the layout thread to communicate to the constellation.