feat: MessagePorts in the main process (#22404)

lib/browser/api/message-channel.ts

@@ -0,0 +1,12 @@
+import { MessagePortMain } from '@electron/internal/browser/message-port-main'
+const { createPair } = process.electronBinding('message_port')
+
+export default class MessageChannelMain {
+  port1: MessagePortMain;
+  port2: MessagePortMain;
+  constructor () {
+    const { port1, port2 } = createPair()
+    this.port1 = new MessagePortMain(port1)
+    this.port2 = new MessagePortMain(port2)
+  }
+}

lib/browser/api/module-keys.js

@@ -24,6 +24,7 @@ module.exports = [
   { name: 'nativeTheme' },
   { name: 'net' },
   { name: 'netLog' },
+  { name: 'MessageChannelMain' },
   { name: 'Notification' },
   { name: 'powerMonitor' },
   { name: 'powerSaveBlocker' },

lib/browser/api/module-list.ts

@@ -16,6 +16,7 @@ export const browserModuleList: ElectronInternal.ModuleEntry[] = [
   { name: 'inAppPurchase', loader: () => require('./in-app-purchase') },
   { name: 'Menu', loader: () => require('./menu') },
   { name: 'MenuItem', loader: () => require('./menu-item') },
+  { name: 'MessageChannelMain', loader: () => require('./message-channel') },
   { name: 'nativeTheme', loader: () => require('./native-theme') },
   { name: 'net', loader: () => require('./net') },
   { name: 'netLog', loader: () => require('./net-log') },

lib/browser/api/web-contents.js

@@ -11,6 +11,7 @@ const { internalWindowOpen } = require('@electron/internal/browser/guest-window-
 const NavigationController = require('@electron/internal/browser/navigation-controller')
 const { ipcMainInternal } = require('@electron/internal/browser/ipc-main-internal')
 const ipcMainUtils = require('@electron/internal/browser/ipc-main-internal-utils')
+const { MessagePortMain } = require('@electron/internal/browser/message-port-main')
 
 // session is not used here, the purpose is to make sure session is initalized
 // before the webContents module.
@@ -115,6 +116,13 @@ WebContents.prototype.send = function (channel, ...args) {
   return this._send(internal, sendToAll, channel, args)
 }
 
+WebContents.prototype.postMessage = function (...args) {
+  if (Array.isArray(args[2])) {
+    args[2] = args[2].map(o => o instanceof MessagePortMain ? o._internalPort : o)
+  }
+  this._postMessage(...args)
+}
+
 WebContents.prototype.sendToAll = function (channel, ...args) {
   if (typeof channel !== 'string') {
     throw new Error('Missing required channel argument')
@@ -472,6 +480,11 @@ WebContents.prototype._init = function () {
     }
   })
 
+  this.on('-ipc-ports', function (event, internal, channel, message, ports) {
+    event.ports = ports.map(p => new MessagePortMain(p))
+    ipcMain.emit(channel, event, message)
+  })
+
   // Handle context menu action request from pepper plugin.
   this.on('pepper-context-menu', function (event, params, callback) {
     // Access Menu via electron.Menu to prevent circular require.