1 files changed, 111 insertions, 0 deletions
diff --git a/remote/shared/messagehandler/transports/js-window-actors/MessageHandlerFrameChild.sys.mjs b/remote/shared/messagehandler/transports/js-window-actors/MessageHandlerFrameChild.sys.mjs
new file mode 100644
index 0000000000..52a8fdc4c9
--- /dev/null
+++ b/remote/shared/messagehandler/transports/js-window-actors/MessageHandlerFrameChild.sys.mjs
@@ -0,0 +1,111 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  isBrowsingContextCompatible:
+    "chrome://remote/content/shared/messagehandler/transports/BrowsingContextUtils.sys.mjs",
+  MessageHandlerRegistry:
+    "chrome://remote/content/shared/messagehandler/MessageHandlerRegistry.sys.mjs",
+  WindowGlobalMessageHandler:
+    "chrome://remote/content/shared/messagehandler/WindowGlobalMessageHandler.sys.mjs",
+});
+
+/**
+ * Map from MessageHandlerRegistry to MessageHandlerFrameChild actor. This will
+ * allow a WindowGlobalMessageHandler to find the JSWindowActorChild instance to
+ * use to send commands.
+ */
+const registryToActor = new WeakMap();
+
+/**
+ * Retrieve the MessageHandlerFrameChild which is linked to the provided
+ * WindowGlobalMessageHandler instance.
+ *
+ * @param {WindowGlobalMessageHandler} messageHandler
+ *     The WindowGlobalMessageHandler for which to get the JSWindowActor.
+ * @returns {MessageHandlerFrameChild}
+ *     The corresponding MessageHandlerFrameChild instance.
+ */
+export function getMessageHandlerFrameChildActor(messageHandler) {
+  return registryToActor.get(messageHandler.registry);
+}
+
+/**
+ * Child actor for the MessageHandlerFrame JSWindowActor. The
+ * MessageHandlerFrame actor is used by RootTransport to communicate between
+ * ROOT MessageHandlers and WINDOW_GLOBAL MessageHandlers.
+ */
+export class MessageHandlerFrameChild extends JSWindowActorChild {
+  actorCreated() {
+    this.type = lazy.WindowGlobalMessageHandler.type;
+    this.context = this.manager.browsingContext;
+
+    this._registry = new lazy.MessageHandlerRegistry(this.type, this.context);
+    registryToActor.set(this._registry, this);
+
+    this._onRegistryEvent = this._onRegistryEvent.bind(this);
+
+    // MessageHandlerFrameChild is responsible for forwarding events from
+    // WindowGlobalMessageHandler to the parent process.
+    // Such events are re-emitted on the MessageHandlerRegistry to avoid
+    // setting up listeners on individual MessageHandler instances.
+    this._registry.on("message-handler-registry-event", this._onRegistryEvent);
+  }
+
+  handleEvent({ persisted, type }) {
+    if (type == "DOMWindowCreated" || (type == "pageshow" && persisted)) {
+      // When the window is created or is retrieved from BFCache, instantiate
+      // a MessageHandler for all sessions which might need it.
+      if (lazy.isBrowsingContextCompatible(this.manager.browsingContext)) {
+        this._registry.createAllMessageHandlers();
+      }
+    } else if (type == "pagehide" && persisted) {
+      // When the page is moved to BFCache, all the currently created message
+      // handlers should be destroyed.
+      this._registry.destroy();
+    }
+  }
+
+  async receiveMessage(message) {
+    if (message.name === "MessageHandlerFrameParent:sendCommand") {
+      const { sessionId, command } = message.data;
+      const messageHandler =
+        this._registry.getOrCreateMessageHandler(sessionId);
+      try {
+        return await messageHandler.handleCommand(command);
+      } catch (e) {
+        if (e?.isRemoteError) {
+          return {
+            error: e.toJSON(),
+            isMessageHandlerError: e.isMessageHandlerError,
+          };
+        }
+        throw e;
+      }
+    }
+
+    return null;
+  }
+
+  sendCommand(command, sessionId) {
+    return this.sendQuery("MessageHandlerFrameChild:sendCommand", {
+      command,
+      sessionId,
+    });
+  }
+
+  _onRegistryEvent(eventName, wrappedEvent) {
+    this.sendAsyncMessage(
+      "MessageHandlerFrameChild:messageHandlerEvent",
+      wrappedEvent
+    );
+  }
+
+  didDestroy() {
+    this._registry.off("message-handler-registry-event", this._onRegistryEvent);
+    this._registry.destroy();
+  }
+}