1 files changed, 146 insertions, 0 deletions
diff --git a/b2g/components/Frames.jsm b/b2g/components/Frames.jsm
new file mode 100644
index 000000000..0eb00cb4c
--- /dev/null
+++ b/b2g/components/Frames.jsm
@@ -0,0 +1,146 @@
+/* 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';
+
+this.EXPORTED_SYMBOLS = ['Frames'];
+
+const Cu = Components.utils;
+const Ci = Components.interfaces;
+
+Cu.import('resource://gre/modules/Services.jsm');
+Cu.import('resource://gre/modules/SystemAppProxy.jsm');
+
+const listeners = [];
+
+const Observer = {
+  // Save a map of (MessageManager => Frame) to be able to dispatch
+  // the FrameDestroyed event with a frame reference.
+  _frames: new Map(),
+
+  // Also save current number of iframes opened by app
+  _apps: new Map(),
+
+  start: function () {
+    Services.obs.addObserver(this, 'remote-browser-shown', false);
+    Services.obs.addObserver(this, 'inprocess-browser-shown', false);
+    Services.obs.addObserver(this, 'message-manager-close', false);
+
+    SystemAppProxy.getFrames().forEach(frame => {
+      let mm = frame.QueryInterface(Ci.nsIFrameLoaderOwner).frameLoader.messageManager;
+      this._frames.set(mm, frame);
+      let mozapp = frame.getAttribute('mozapp');
+      if (mozapp) {
+        this._apps.set(mozapp, (this._apps.get(mozapp) || 0) + 1);
+      }
+    });
+  },
+
+  stop: function () {
+    Services.obs.removeObserver(this, 'remote-browser-shown');
+    Services.obs.removeObserver(this, 'inprocess-browser-shown');
+    Services.obs.removeObserver(this, 'message-manager-close');
+    this._frames.clear();
+    this._apps.clear();
+  },
+
+  observe: function (subject, topic, data) {
+    switch(topic) {
+
+      // Listen for frame creation in OOP (device) as well as in parent process (b2g desktop)
+      case 'remote-browser-shown':
+      case 'inprocess-browser-shown':
+        let frameLoader = subject;
+
+        // get a ref to the app <iframe>
+        frameLoader.QueryInterface(Ci.nsIFrameLoader);
+        let frame = frameLoader.ownerElement;
+        let mm = frame.QueryInterface(Ci.nsIFrameLoaderOwner).frameLoader.messageManager;
+        this.onMessageManagerCreated(mm, frame);
+        break;
+
+      // Every time an iframe is destroyed, its message manager also is
+      case 'message-manager-close':
+        this.onMessageManagerDestroyed(subject);
+        break;
+    }
+  },
+
+  onMessageManagerCreated: function (mm, frame) {
+    this._frames.set(mm, frame);
+
+    let isFirstAppFrame = null;
+    let mozapp = frame.getAttribute('mozapp');
+    if (mozapp) {
+      let count = (this._apps.get(mozapp) || 0) + 1;
+      this._apps.set(mozapp, count);
+      isFirstAppFrame = (count === 1);
+    }
+
+    listeners.forEach(function (listener) {
+      try {
+        listener.onFrameCreated(frame, isFirstAppFrame);
+      } catch(e) {
+        dump('Exception while calling Frames.jsm listener:' + e + '\n' +
+             e.stack + '\n');
+      }
+    });
+  },
+
+  onMessageManagerDestroyed: function (mm) {
+    let frame = this._frames.get(mm);
+    if (!frame) {
+      // We received an event for an unknown message manager
+      return;
+    }
+
+    this._frames.delete(mm);
+
+    let isLastAppFrame = null;
+    let mozapp = frame.getAttribute('mozapp');
+    if (mozapp) {
+      let count = (this._apps.get(mozapp) || 0) - 1;
+      this._apps.set(mozapp, count);
+      isLastAppFrame = (count === 0);
+    }
+
+    listeners.forEach(function (listener) {
+      try {
+        listener.onFrameDestroyed(frame, isLastAppFrame);
+      } catch(e) {
+        dump('Exception while calling Frames.jsm listener:' + e + '\n' +
+             e.stack + '\n');
+      }
+    });
+  }
+
+};
+
+var Frames = this.Frames = {
+
+  list: () => SystemAppProxy.getFrames(),
+
+  addObserver: function (listener) {
+    if (listeners.indexOf(listener) !== -1) {
+      return;
+    }
+
+    listeners.push(listener);
+    if (listeners.length == 1) {
+      Observer.start();
+    }
+  },
+
+  removeObserver: function (listener) {
+    let idx = listeners.indexOf(listener);
+    if (idx !== -1) {
+      listeners.splice(idx, 1);
+    }
+    if (listeners.length === 0) {
+      Observer.stop();
+    }
+  }
+
+};
+