feat: use default-app behavior in packaged apps (#16310)

Unify the behavior between default app and packaged apps:
- create default application menu unless the app has one
- default window-all-closed handling unless the app handles the event

lib/browser/api/menu.js

@@ -145,6 +145,8 @@ Menu.setApplicationMenu = function (menu) {
   }
 
   applicationMenu = menu
+  v8Util.setHiddenValue(global, 'applicationMenuSet', true)
+
   if (process.platform === 'darwin') {
     if (!menu) return
     menu._callMenuWillShow()

lib/browser/default-menu.js

@@ -0,0 +1,58 @@
+'use strict'
+
+const { shell, Menu } = require('electron')
+const v8Util = process.atomBinding('v8_util')
+
+const isMac = process.platform === 'darwin'
+
+const setDefaultApplicationMenu = () => {
+  if (v8Util.getHiddenValue(global, 'applicationMenuSet')) return
+
+  const helpMenu = {
+    role: 'help',
+    submenu: [
+      {
+        label: 'Learn More',
+        click () {
+          shell.openExternalSync('https://electronjs.org')
+        }
+      },
+      {
+        label: 'Documentation',
+        click () {
+          shell.openExternalSync(
+            `https://github.com/electron/electron/tree/v${process.versions.electron}/docs#readme`
+          )
+        }
+      },
+      {
+        label: 'Community Discussions',
+        click () {
+          shell.openExternalSync('https://discuss.atom.io/c/electron')
+        }
+      },
+      {
+        label: 'Search Issues',
+        click () {
+          shell.openExternalSync('https://github.com/electron/electron/issues')
+        }
+      }
+    ]
+  }
+
+  const template = [
+    ...(isMac ? [{ role: 'appMenu' }] : []),
+    { role: 'fileMenu' },
+    { role: 'editMenu' },
+    { role: 'viewMenu' },
+    { role: 'windowMenu' },
+    helpMenu
+  ]
+
+  const menu = Menu.buildFromTemplate(template)
+  Menu.setApplicationMenu(menu)
+}
+
+module.exports = {
+  setDefaultApplicationMenu
+}

lib/browser/init.js

@@ -184,5 +184,17 @@ if (currentPlatformSupportsAppIndicator()) {
   process.env.XDG_CURRENT_DESKTOP = 'Unity'
 }
 
+// Quit when all windows are closed and no other one is listening to this.
+app.on('window-all-closed', () => {
+  if (app.listenerCount('window-all-closed') === 1) {
+    app.quit()
+  }
+})
+
+const { setDefaultApplicationMenu } = require('@electron/internal/browser/default-menu')
+
+// Create default menu.
+app.once('ready', setDefaultApplicationMenu)
+
 // Finally load app's main.js and transfer control to C++.
 Module._load(path.join(packagePath, mainStartupScript), Module, true)