1 files changed, 75 insertions, 0 deletions
diff --git a/remote/domains/Domain.jsm b/remote/domains/Domain.jsm
new file mode 100644
index 0000000000..4887d4dc74
--- /dev/null
+++ b/remote/domains/Domain.jsm
@@ -0,0 +1,75 @@
+/* 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/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["Domain"];
+
+class Domain {
+  constructor(session) {
+    this.session = session;
+    this.name = this.constructor.name;
+
+    this.eventListeners_ = new Set();
+    this._requestCounter = 0;
+  }
+
+  destructor() {}
+
+  emit(eventName, params = {}) {
+    for (const listener of this.eventListeners_) {
+      try {
+        if (isEventHandler(listener)) {
+          listener.onEvent(eventName, params);
+        } else {
+          listener.call(this, eventName, params);
+        }
+      } catch (e) {
+        Cu.reportError(e);
+      }
+    }
+  }
+
+  /**
+   * Execute the provided method in the child domain that has the same domain
+   * name. eg. calling this.executeInChild from domains/parent/Input.jsm will
+   * attempt to execute the method in domains/content/Input.jsm.
+   *
+   * This can only be called from parent domains managed by a TabSession.
+   *
+   * @param {String} method
+   *        Name of the method to call on the child domain.
+   * @param {Object} params
+   *        Optional parameters. Must be serializable.
+   */
+  executeInChild(method, params) {
+    if (!this.session.executeInChild) {
+      throw new Error(
+        "executeInChild can only be used in Domains managed by a TabSession"
+      );
+    }
+    this._requestCounter++;
+    const id = this.name + "-" + this._requestCounter;
+    return this.session.executeInChild(id, this.name, method, params);
+  }
+
+  addEventListener(listener) {
+    if (typeof listener != "function" && !isEventHandler(listener)) {
+      throw new TypeError();
+    }
+    this.eventListeners_.add(listener);
+  }
+
+  // static
+
+  static implements(command) {
+    return command && typeof this.prototype[command] == "function";
+  }
+}
+
+function isEventHandler(listener) {
+  return (
+    listener && "onEvent" in listener && typeof listener.onEvent == "function"
+  );
+}