Merge pull request #7407 from thomsonreuters/New_Window_Handler_Can_Create_And_Return_Window

New-window event handler can return its own BrowserWindow instance

docs/api/web-contents.md

@@ -155,7 +155,9 @@ requested by `window.open` or an external link like `<a target='_blank'>`.
 
 By default a new `BrowserWindow` will be created for the `url`.
 
-Calling `event.preventDefault()` will prevent creating new windows.
+Calling `event.preventDefault()` will prevent creating new windows. In such case, the
+`event.newGuest` may be set with a reference to a `BrowserWindow` instance to make it
+used by the Electron's runtime.
 
 #### Event: 'will-navigate'
 

lib/browser/guest-window-manager.js

@@ -40,22 +40,62 @@ const mergeBrowserWindowOptions = function (embedder, options) {
     options.webPreferences.nodeIntegration = false
   }
 
+  // Sets correct openerId here to give correct options to 'new-window' event handler
+  options.webPreferences.openerId = embedder.id
+
   return options
 }
 
+// Setup a new guest with |embedder|
+const setupGuest = function (embedder, frameName, guest, options) {
+  // When |embedder| is destroyed we should also destroy attached guest, and if
+  // guest is closed by user then we should prevent |embedder| from double
+  // closing guest.
+  const guestId = guest.webContents.id
+  const closedByEmbedder = function () {
+    guest.removeListener('closed', closedByUser)
+    guest.destroy()
+  }
+  const closedByUser = function () {
+    embedder.send('ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_CLOSED_' + guestId)
+    embedder.removeListener('render-view-deleted', closedByEmbedder)
+  }
+  if (!options.webPreferences.sandbox) {
+    // These events should only be handled when the guest window is opened by a
+    // non-sandboxed renderer for two reasons:
+    //
+    // - `render-view-deleted` is emitted when the popup is closed by the user,
+    //   and that will eventually result in NativeWindow::NotifyWindowClosed
+    //   using a dangling pointer since `destroy()` would have been called by
+    //   `closeByEmbedded`
+    // - No need to emit `ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_CLOSED_` since
+    //   there's no renderer code listening to it.,
+    embedder.once('render-view-deleted', closedByEmbedder)
+    guest.once('closed', closedByUser)
+  }
+  if (frameName) {
+    frameToGuest[frameName] = guest
+    guest.frameName = frameName
+    guest.once('closed', function () {
+      delete frameToGuest[frameName]
+    })
+  }
+  return guestId
+}
+
 // Create a new guest created by |embedder| with |options|.
 const createGuest = function (embedder, url, frameName, options) {
   let guest = frameToGuest[frameName]
   if (frameName && (guest != null)) {
     guest.loadURL(url)
-    return guest.id
+    return guest.webContents.id
   }
 
   // Remember the embedder window's id.
   if (options.webPreferences == null) {
     options.webPreferences = {}
   }
-  options.webPreferences.openerId = embedder.id
+
   guest = new BrowserWindow(options)
   if (!options.webContents || url !== 'about:blank') {
     // We should not call `loadURL` if the window was constructed from an
@@ -82,42 +122,7 @@ const createGuest = function (embedder, url, frameName, options) {
     guest.loadURL(url)
   }
 
-  // When |embedder| is destroyed we should also destroy attached guest, and if
+  return setupGuest(embedder, frameName, guest, options)
-  // guest is closed by user then we should prevent |embedder| from double
-  // closing guest.
-  const guestId = guest.webContents.id
-
-  const closedByEmbedder = function () {
-    guest.removeListener('closed', closedByUser)
-    guest.destroy()
-  }
-  const closedByUser = function () {
-    embedder.send('ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_CLOSED_' + guestId)
-    embedder.removeListener('render-view-deleted', closedByEmbedder)
-  }
-  if (!options.webPreferences.sandbox) {
-    // These events should only be handled when the guest window is opened by a
-    // non-sandboxed renderer for two reasons:
-    //
-    // - `render-view-deleted` is emitted when the popup is closed by the user,
-    //   and that will eventually result in NativeWindow::NotifyWindowClosed
-    //   using a dangling pointer since `destroy()` would have been called by
-    //   `closeByEmbedded`
-    // - No need to emit `ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_CLOSED_` since
-    //   there's no renderer code listening to it.,
-    embedder.once('render-view-deleted', closedByEmbedder)
-    guest.once('closed', closedByUser)
-  }
-
-  if (frameName) {
-    frameToGuest[frameName] = guest
-    guest.frameName = frameName
-    guest.once('closed', function () {
-      delete frameToGuest[frameName]
-    })
-  }
-
-  return guestId
 }
 
 const getGuestWindow = function (guestId) {
@@ -138,8 +143,13 @@ const getGuestWindow = function (guestId) {
 ipcMain.on('ELECTRON_GUEST_WINDOW_MANAGER_WINDOW_OPEN', function (event, url, frameName, disposition, options, additionalFeatures) {
   options = mergeBrowserWindowOptions(event.sender, options)
   event.sender.emit('new-window', event, url, frameName, disposition, options, additionalFeatures)
+  const newGuest = event.newGuest
   if ((event.sender.isGuest() && !event.sender.allowPopups) || event.defaultPrevented) {
-    event.returnValue = null
+    if (newGuest !== undefined && newGuest !== null) {
+      event.returnValue = setupGuest(event.sender, frameName, newGuest, options)
+    } else {
+      event.returnValue = null
+    }
   } else {
     event.returnValue = createGuest(event.sender, url, frameName, options)
   }