1 files changed, 276 insertions, 0 deletions
diff --git a/dom/browser-element/BrowserElementParent.jsm b/dom/browser-element/BrowserElementParent.jsm
new file mode 100644
index 0000000000..ec342dace2
--- /dev/null
+++ b/dom/browser-element/BrowserElementParent.jsm
@@ -0,0 +1,276 @@
+/* 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";
+
+/* BrowserElementParent injects script to listen for certain events in the
+ * child.  We then listen to messages from the child script and take
+ * appropriate action here in the parent.
+ */
+
+const { BrowserElementPromptService } = ChromeUtils.import(
+  "resource://gre/modules/BrowserElementPromptService.jsm"
+);
+
+function debug(msg) {
+  // dump("BrowserElementParent - " + msg + "\n");
+}
+
+function handleWindowEvent(e) {
+  if (this._browserElementParents) {
+    let beps = ChromeUtils.nondeterministicGetWeakMapKeys(
+      this._browserElementParents
+    );
+    beps.forEach(bep => bep._handleOwnerEvent(e));
+  }
+}
+
+function BrowserElementParent() {
+  debug("Creating new BrowserElementParent object");
+}
+
+BrowserElementParent.prototype = {
+  classDescription: "BrowserElementAPI implementation",
+  classID: Components.ID("{9f171ac4-0939-4ef8-b360-3408aedc3060}"),
+  contractID: "@mozilla.org/dom/browser-element-api;1",
+  QueryInterface: ChromeUtils.generateQI([
+    "nsIBrowserElementAPI",
+    "nsISupportsWeakReference",
+  ]),
+
+  setFrameLoader(frameLoader) {
+    debug("Setting frameLoader");
+    this._frameLoader = frameLoader;
+    this._frameElement = frameLoader.ownerElement;
+    if (!this._frameElement) {
+      debug("No frame element?");
+      return;
+    }
+    // Listen to visibilitychange on the iframe's owner window, and forward
+    // changes down to the child.  We want to do this while registering as few
+    // visibilitychange listeners on _window as possible, because such a listener
+    // may live longer than this BrowserElementParent object.
+    //
+    // To accomplish this, we register just one listener on the window, and have
+    // it reference a WeakMap whose keys are all the BrowserElementParent objects
+    // on the window.  Then when the listener fires, we iterate over the
+    // WeakMap's keys (which we can do, because we're chrome) to notify the
+    // BrowserElementParents.
+    if (!this._window._browserElementParents) {
+      this._window._browserElementParents = new WeakMap();
+      let handler = handleWindowEvent.bind(this._window);
+      let windowEvents = ["visibilitychange"];
+      for (let event of windowEvents) {
+        Services.els.addSystemEventListener(
+          this._window,
+          event,
+          handler,
+          /* useCapture = */ true
+        );
+      }
+    }
+
+    this._window._browserElementParents.set(this, null);
+
+    // Insert ourself into the prompt service.
+    BrowserElementPromptService.mapFrameToBrowserElementParent(
+      this._frameElement,
+      this
+    );
+    this._setupMessageListener();
+  },
+
+  destroyFrameScripts() {
+    debug("Destroying frame scripts");
+    this._mm.sendAsyncMessage("browser-element-api:destroy");
+  },
+
+  _setupMessageListener() {
+    this._mm = this._frameLoader.messageManager;
+    this._mm.addMessageListener("browser-element-api:call", this);
+  },
+
+  receiveMessage(aMsg) {
+    if (!this._isAlive()) {
+      return undefined;
+    }
+
+    // Messages we receive are handed to functions which take a (data) argument,
+    // where |data| is the message manager's data object.
+    // We use a single message and dispatch to various function based
+    // on data.msg_name
+    let mmCalls = {
+      hello: this._recvHello,
+    };
+
+    let mmSecuritySensitiveCalls = {
+      showmodalprompt: this._handleShowModalPrompt,
+    };
+
+    if (aMsg.data.msg_name in mmCalls) {
+      return mmCalls[aMsg.data.msg_name].apply(this, arguments);
+    } else if (aMsg.data.msg_name in mmSecuritySensitiveCalls) {
+      return mmSecuritySensitiveCalls[aMsg.data.msg_name].apply(
+        this,
+        arguments
+      );
+    }
+    return undefined;
+  },
+
+  _removeMessageListener() {
+    this._mm.removeMessageListener("browser-element-api:call", this);
+  },
+
+  /**
+   * You shouldn't touch this._frameElement or this._window if _isAlive is
+   * false.  (You'll likely get an exception if you do.)
+   */
+  _isAlive() {
+    return (
+      !Cu.isDeadWrapper(this._frameElement) &&
+      !Cu.isDeadWrapper(this._frameElement.ownerDocument) &&
+      !Cu.isDeadWrapper(this._frameElement.ownerGlobal)
+    );
+  },
+
+  get _window() {
+    return this._frameElement.ownerGlobal;
+  },
+
+  _sendAsyncMsg(msg, data) {
+    try {
+      if (!data) {
+        data = {};
+      }
+
+      data.msg_name = msg;
+      this._mm.sendAsyncMessage("browser-element-api:call", data);
+    } catch (e) {
+      return false;
+    }
+    return true;
+  },
+
+  _recvHello() {
+    debug("recvHello");
+
+    // Inform our child if our owner element's document is invisible.  Note
+    // that we must do so here, rather than in the BrowserElementParent
+    // constructor, because the BrowserElementChild may not be initialized when
+    // we run our constructor.
+    if (this._window.document.hidden) {
+      this._ownerVisibilityChange();
+    }
+  },
+
+  /**
+   * Fire either a vanilla or a custom event, depending on the contents of
+   * |data|.
+   */
+  _fireEventFromMsg(data) {
+    let detail = data.json;
+    let name = detail.msg_name;
+
+    // For events that send a "_payload_" property, we just want to transmit
+    // this in the event.
+    if ("_payload_" in detail) {
+      detail = detail._payload_;
+    }
+
+    debug("fireEventFromMsg: " + name + ", " + JSON.stringify(detail));
+    let evt = this._createEvent(name, detail, /* cancelable = */ false);
+    this._frameElement.dispatchEvent(evt);
+  },
+
+  _handleShowModalPrompt(data) {
+    // Fire a showmodalprmopt event on the iframe.  When this method is called,
+    // the child is spinning in a nested event loop waiting for an
+    // unblock-modal-prompt message.
+    //
+    // If the embedder calls preventDefault() on the showmodalprompt event,
+    // we'll block the child until event.detail.unblock() is called.
+    //
+    // Otherwise, if preventDefault() is not called, we'll send the
+    // unblock-modal-prompt message to the child as soon as the event is done
+    // dispatching.
+
+    let detail = data.json;
+    debug("handleShowPrompt " + JSON.stringify(detail));
+
+    // Strip off the windowID property from the object we send along in the
+    // event.
+    let windowID = detail.windowID;
+    delete detail.windowID;
+    debug("Event will have detail: " + JSON.stringify(detail));
+    let evt = this._createEvent(
+      "showmodalprompt",
+      detail,
+      /* cancelable = */ true
+    );
+
+    let self = this;
+    let unblockMsgSent = false;
+    function sendUnblockMsg() {
+      if (unblockMsgSent) {
+        return;
+      }
+      unblockMsgSent = true;
+
+      // We don't need to sanitize evt.detail.returnValue (e.g. converting the
+      // return value of confirm() to a boolean); Gecko does that for us.
+
+      let data = { windowID, returnValue: evt.detail.returnValue };
+      self._sendAsyncMsg("unblock-modal-prompt", data);
+    }
+
+    Cu.exportFunction(sendUnblockMsg, evt.detail, { defineAs: "unblock" });
+
+    this._frameElement.dispatchEvent(evt);
+
+    if (!evt.defaultPrevented) {
+      // Unblock the inner frame immediately.  Otherwise we'll unblock upon
+      // evt.detail.unblock().
+      sendUnblockMsg();
+    }
+  },
+
+  _createEvent(evtName, detail, cancelable) {
+    // This will have to change if we ever want to send a CustomEvent with null
+    // detail.  For now, it's OK.
+    if (detail !== undefined && detail !== null) {
+      detail = Cu.cloneInto(detail, this._window);
+      return new this._window.CustomEvent("mozbrowser" + evtName, {
+        bubbles: true,
+        cancelable,
+        detail,
+      });
+    }
+
+    return new this._window.Event("mozbrowser" + evtName, {
+      bubbles: true,
+      cancelable,
+    });
+  },
+
+  _handleOwnerEvent(evt) {
+    switch (evt.type) {
+      case "visibilitychange":
+        this._ownerVisibilityChange();
+        break;
+    }
+  },
+
+  /**
+   * Called when the visibility of the window which owns this iframe changes.
+   */
+  _ownerVisibilityChange() {
+    let bc = this._frameLoader?.browsingContext;
+    if (bc) {
+      bc.isActive = !this._window.document.hidden;
+    }
+  },
+};
+
+var EXPORTED_SYMBOLS = ["BrowserElementParent"];