Auto merge of #20661 - cbrewster:history_state_discard, r=asajeffrey

Remove insaccessible history states

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components/script/dom/history.rs

@@ -103,6 +103,13 @@ impl History {
         }
     }
 
+    pub fn remove_states(&self, states: Vec<HistoryStateId>) {
+        let _ = self.window
+            .upcast::<GlobalScope>()
+            .resource_threads()
+            .send(CoreResourceMsg::RemoveHistoryStates(states));
+    }
+
     // https://html.spec.whatwg.org/multipage/#dom-history-pushstate
     // https://html.spec.whatwg.org/multipage/#dom-history-replacestate
     fn push_or_replace_state(&self,

components/script/script_thread.rs

@@ -1170,6 +1170,7 @@ impl ScriptThread {
                     PostMessage(id, ..) => Some(id),
                     UpdatePipelineId(_, _, id, _) => Some(id),
                     UpdateHistoryStateId(id, ..) => Some(id),
+                    RemoveHistoryStates(id, ..) => Some(id),
                     FocusIFrame(id, ..) => Some(id),
                     WebDriverScriptCommand(id, ..) => Some(id),
                     TickAllAnimations(id) => Some(id),
@@ -1298,6 +1299,8 @@ impl ScriptThread {
                                                reason),
             ConstellationControlMsg::UpdateHistoryStateId(pipeline_id, history_state_id) =>
                 self.handle_update_history_state_id_msg(pipeline_id, history_state_id),
+            ConstellationControlMsg::RemoveHistoryStates(pipeline_id, history_states) =>
+                self.handle_remove_history_states(pipeline_id, history_states),
             ConstellationControlMsg::FocusIFrame(parent_pipeline_id, frame_id) =>
                 self.handle_focus_iframe_msg(parent_pipeline_id, frame_id),
             ConstellationControlMsg::WebDriverScriptCommand(pipeline_id, msg) =>
@@ -1683,6 +1686,13 @@ impl ScriptThread {
         }
     }
 
+    fn handle_remove_history_states(&self, pipeline_id: PipelineId, history_states: Vec<HistoryStateId>) {
+        match { self.documents.borrow().find_window(pipeline_id) } {
+            None => return warn!("update history state after pipeline {} closed.", pipeline_id),
+            Some(window) => window.History().r().remove_states(history_states),
+        }
+    }
+
     /// Window was resized, but this script was not active, so don't reflow yet
     fn handle_resize_inactive_msg(&self, id: PipelineId, new_size: WindowSizeData) {
         let window = self.documents.borrow().find_window(id)