1 files changed, 53 insertions, 0 deletions
diff --git a/toolkit/jetpack/sdk/windows/observer.js b/toolkit/jetpack/sdk/windows/observer.js
new file mode 100644
index 000000000..5ba2535f1
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+++ b/toolkit/jetpack/sdk/windows/observer.js
@@ -0,0 +1,53 @@
+/* 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";
+
+module.metadata = {
+  "stability": "unstable"
+};
+
+const { EventTarget } = require("../event/target");
+const { emit } = require("../event/core");
+const { WindowTracker, windowIterator } = require("../deprecated/window-utils");
+const { DOMEventAssembler } = require("../deprecated/events/assembler");
+const { Class } = require("../core/heritage");
+const { Cu } = require("chrome");
+
+// Event emitter objects used to register listeners and emit events on them
+// when they occur.
+const Observer = Class({
+  initialize() {
+    // Using `WindowTracker` to track window events.
+    WindowTracker({
+      onTrack: chromeWindow => {
+        emit(this, "open", chromeWindow);
+        this.observe(chromeWindow);
+      },
+      onUntrack: chromeWindow => {
+        emit(this, "close", chromeWindow);
+        this.ignore(chromeWindow);
+      }
+    });
+  },
+  implements: [EventTarget, DOMEventAssembler],
+  /**
+   * Events that are supported and emitted by the module.
+   */
+  supportedEventsTypes: [ "activate", "deactivate" ],
+  /**
+   * Function handles all the supported events on all the windows that are
+   * observed. Method is used to proxy events to the listeners registered on
+   * this event emitter.
+   * @param {Event} event
+   *    Keyboard event being emitted.
+   */
+  handleEvent(event) {
+    // Ignore events from windows in the child process as they can't be top-level
+    if (Cu.isCrossProcessWrapper(event.target))
+      return;
+    emit(this, event.type, event.target, event);
+  }
+});
+
+exports.observer = new Observer();