fix: <webview> not working with contextIsolation + sandbox (#16469)

lib/renderer/web-view/web-view-init.js

@@ -0,0 +1,35 @@
+'use strict'
+
+const ipcRenderer = require('@electron/internal/renderer/ipc-renderer-internal')
+const v8Util = process.atomBinding('v8_util')
+
+function handleFocusBlur (guestInstanceId) {
+  // Note that while Chromium content APIs have observer for focus/blur, they
+  // unfortunately do not work for webview.
+
+  window.addEventListener('focus', () => {
+    ipcRenderer.send('ELECTRON_GUEST_VIEW_MANAGER_FOCUS_CHANGE', true, guestInstanceId)
+  })
+
+  window.addEventListener('blur', () => {
+    ipcRenderer.send('ELECTRON_GUEST_VIEW_MANAGER_FOCUS_CHANGE', false, guestInstanceId)
+  })
+}
+
+module.exports = function (contextIsolation, webviewTag, guestInstanceId) {
+  // Load webview tag implementation.
+  if (webviewTag && guestInstanceId == null) {
+    const webViewImpl = require('@electron/internal/renderer/web-view/web-view-impl')
+    if (contextIsolation) {
+      v8Util.setHiddenValue(window, 'web-view-impl', webViewImpl)
+    } else {
+      const { setupWebView } = require('@electron/internal/renderer/web-view/web-view-element')
+      setupWebView(v8Util, webViewImpl)
+    }
+  }
+
+  if (guestInstanceId) {
+    // Report focus/blur events of webview to browser.
+    handleFocusBlur(guestInstanceId)
+  }
+}