feat: add webContents.setWindowOpenHandler API (#24517)

Co-authored-by: Jeremy Rose <jeremya@chromium.org>

spec-main/guest-window-manager-spec.ts

@@ -1,15 +1,16 @@
 import { BrowserWindow } from 'electron';
 import { writeFileSync, readFileSync } from 'fs';
 import { resolve } from 'path';
-import { expect } from 'chai';
+import { expect, assert } from 'chai';
 import { closeAllWindows } from './window-helpers';
+const { emittedOnce } = require('./events-helpers');
 
 function genSnapshot (browserWindow: BrowserWindow, features: string) {
   return new Promise((resolve) => {
     browserWindow.webContents.on('new-window', (...args: any[]) => {
       resolve([features, ...args]);
     });
-    browserWindow.webContents.executeJavaScript(`window.open('about:blank', 'frame name', '${features}')`);
+    browserWindow.webContents.executeJavaScript(`window.open('about:blank', 'frame name', '${features}') && true`);
   });
 }
 
@@ -52,7 +53,7 @@ describe('new-window event', () => {
       beforeEach((done) => {
         browserWindow = new BrowserWindow(browserWindowOptions);
         browserWindow.loadURL('about:blank');
-        browserWindow.on('ready-to-show', () => done());
+        browserWindow.on('ready-to-show', () => { done(); });
       });
 
       afterEach(closeAllWindows);
@@ -86,6 +87,100 @@ describe('new-window event', () => {
   }
 });
 
+describe('webContents.setWindowOpenHandler', () => {
+  const testConfig = {
+    native: {
+      browserWindowOptions: {
+        show: false,
+        webPreferences: {
+          nativeWindowOpen: true
+        }
+      }
+    },
+    proxy: {
+      browserWindowOptions: {
+        show: false,
+        webPreferences: {
+          nativeWindowOpen: false
+        }
+      }
+    }
+  };
+
+  for (const testName of Object.keys(testConfig) as (keyof typeof testConfig)[]) {
+    let browserWindow: BrowserWindow;
+    const { browserWindowOptions } = testConfig[testName];
+
+    describe(testName, () => {
+      beforeEach((done) => {
+        browserWindow = new BrowserWindow(browserWindowOptions);
+        browserWindow.loadURL('about:blank');
+        browserWindow.on('ready-to-show', () => { browserWindow.show(); done(); });
+      });
+
+      afterEach(closeAllWindows);
+
+      it('does not fire window creation events if an override returns action: deny', (done) => {
+        browserWindow.webContents.setWindowOpenHandler(() => ({ action: 'deny' }));
+        browserWindow.webContents.on('new-window', () => {
+          assert.fail('new-window should not to be called with an overridden window.open');
+        });
+
+        browserWindow.webContents.on('did-create-window', () => {
+          assert.fail('did-create-window should not to be called with an overridden window.open');
+        });
+
+        browserWindow.webContents.executeJavaScript("window.open('about:blank') && true");
+
+        setTimeout(() => {
+          done();
+        }, 500);
+      });
+
+      it('fires handler with correct params', (done) => {
+        const testFrameName = 'test-frame-name';
+        const testFeatures = 'top=10&left=10&something-unknown';
+        const testUrl = 'app://does-not-exist/';
+        browserWindow.webContents.setWindowOpenHandler(({ url, frameName, features }) => {
+          expect(url).to.equal(testUrl);
+          expect(frameName).to.equal(testFrameName);
+          expect(features).to.equal(testFeatures);
+          done();
+          return { action: 'deny' };
+        });
+
+        browserWindow.webContents.executeJavaScript(`window.open('${testUrl}', '${testFrameName}', '${testFeatures}') && true`);
+      });
+
+      it('does fire window creation events if an override returns action: allow', async () => {
+        browserWindow.webContents.setWindowOpenHandler(() => ({ action: 'allow' }));
+
+        setImmediate(() => {
+          browserWindow.webContents.executeJavaScript("window.open('about:blank') && true");
+        });
+
+        await Promise.all([
+          emittedOnce(browserWindow.webContents, 'did-create-window'),
+          emittedOnce(browserWindow.webContents, 'new-window')
+        ]);
+      });
+
+      it('can change webPreferences of child windows', (done) => {
+        browserWindow.webContents.setWindowOpenHandler(() => ({ action: 'allow', overrideBrowserWindowOptions: { webPreferences: { defaultFontSize: 30 } } }));
+
+        browserWindow.webContents.on('did-create-window', async (childWindow) => {
+          await childWindow.webContents.executeJavaScript("document.write('hello')");
+          const size = await childWindow.webContents.executeJavaScript("getComputedStyle(document.querySelector('body')).fontSize");
+          expect(size).to.equal('30px');
+          done();
+        });
+
+        browserWindow.webContents.executeJavaScript("window.open('about:blank') && true");
+      });
+    });
+  }
+});
+
 function stringifySnapshots (snapshots: any, pretty = false) {
   return JSON.stringify(snapshots, (key, value) => {
     if (['sender', 'webContents'].includes(key)) {