fix(electron): do not use --require to throttle startup (#4006)

src/server/electron/electron.ts

@@ -14,7 +14,6 @@
  * limitations under the License.
  */
 
-import * as path from 'path';
 import * as os from 'os';
 import { CRBrowser, CRBrowserContext } from '../chromium/crBrowser';
 import { CRConnection, CRSession } from '../chromium/crConnection';
@@ -77,17 +76,18 @@ export class ElectronApplication extends EventEmitter {
   private async _onPage(page: ElectronPage) {
     // Needs to be sync.
     const windowId = ++this._lastWindowId;
-    // Can be async.
-    const handle = await this._nodeElectronHandle!.evaluateHandle(({ BrowserWindow }, windowId) => BrowserWindow.fromId(windowId), windowId).catch(e => {});
-    if (!handle)
-      return;
-    page.browserWindow = handle;
-    page._browserWindowId = windowId;
     page.on(Page.Events.Close, () => {
       page.browserWindow.dispose();
       this._windows.delete(page);
     });
+    page._browserWindowId = windowId;
     this._windows.add(page);
+
+    // Below is async.
+    const handle = await this._nodeElectronHandle!.evaluateHandle(({ BrowserWindow }, windowId) => BrowserWindow.fromId(windowId), windowId).catch(e => {});
+    if (!handle)
+      return;
+    page.browserWindow = handle;
     await runAbortableTask(progress => page.mainFrame()._waitForLoadState(progress, 'domcontentloaded'), page._timeoutSettings.navigationTimeout({})).catch(e => {}); // can happen after detach
     this.emit(ElectronApplication.Events.Window, page);
   }
@@ -126,16 +126,12 @@ export class ElectronApplication extends EventEmitter {
   }
 
   async _init()  {
-    this._nodeSession.once('Runtime.executionContextCreated', event => {
+    this._nodeSession.on('Runtime.executionContextCreated', (event: any) => {
-      this._nodeExecutionContext = new js.ExecutionContext(new CRExecutionContext(this._nodeSession, event.context));
+      if (event.context.auxData && event.context.auxData.isDefault)
+        this._nodeExecutionContext = new js.ExecutionContext(new CRExecutionContext(this._nodeSession, event.context));
     });
     await this._nodeSession.send('Runtime.enable', {}).catch(e => {});
-    this._nodeElectronHandle = await js.evaluate(this._nodeExecutionContext!, false /* returnByValue */, () => {
+    this._nodeElectronHandle = await js.evaluate(this._nodeExecutionContext!, false /* returnByValue */, `process.mainModule.require('electron')`);
-      // Resolving the race between the debugger and the boot-time script.
-      if ((global as any)._playwrightRun)
-        return (global as any)._playwrightRun();
-      return new Promise(f => (global as any)._playwrightRunCallback = f);
-    });
   }
 }
 
@@ -151,7 +147,7 @@ export class Electron  {
     controller.setLogName('browser');
     return controller.run(async progress => {
       let app: ElectronApplication | undefined = undefined;
-      const electronArguments = ['--inspect=0', '--remote-debugging-port=0', '--require', path.join(__dirname, 'electronLoader.js'), ...args];
+      const electronArguments = ['--inspect=0', '--remote-debugging-port=0', ...args];
 
       if (os.platform() === 'linux') {
         const runningAsRoot = process.geteuid && process.geteuid() === 0;
@@ -171,7 +167,7 @@ export class Electron  {
         cwd: options.cwd,
         tempDirectories: [],
         attemptToGracefullyClose: () => app!.close(),
-        onExit: (exitCode, signal) => {},
+        onExit: () => {},
       });
 
       const nodeMatch = await waitForLine(progress, launchedProcess, launchedProcess.stderr, /^Debugger listening on (ws:\/\/.*)$/);

src/server/electron/electronLoader.ts

@@ -1,72 +0,0 @@
-/**
- * Copyright (c) Microsoft Corporation.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import * as electron from 'electron';
-
-// Electron loader is passed to Electron as --require electronLoader.js and
-// defers the app ready event until remote debugging is established.
-
-(async () => {
-  const app = electron.app;
-  const originalEmitMethod = app.emit.bind(app);
-  const originalIsReadyMethod = app.isReady.bind(app);
-  const originalWhenReadyMethod = app.whenReady.bind(app);
-
-  const deferredEmits: { event: string | symbol, args: any[] }[] = [];
-  let attached = false;
-  let isReady = false;
-  let readyCallback: () => void;
-  const readyPromise = new Promise(f => readyCallback = f);
-
-  app.isReady = () => {
-    if (attached)
-      return originalIsReadyMethod();
-    return isReady;
-  };
-
-  app.whenReady = async () => {
-    if (attached)
-      return originalWhenReadyMethod();
-    await readyPromise;
-  };
-
-  app.emit = (event: string | symbol, ...args: any[]): boolean => {
-    if (attached)
-      return originalEmitMethod(event, ...args);
-    deferredEmits.push({ event, args });
-    return true;
-  };
-
-  const playwrightRun = () => {
-    while (deferredEmits.length) {
-      const emit = deferredEmits.shift();
-      if (emit!.event === 'ready') {
-        isReady = true;
-        readyCallback();
-      }
-      originalEmitMethod(emit!.event, ...emit!.args);
-    }
-    attached = true;
-    return electron;
-  };
-
-  // Resolving the race between the debugger and the boot-time script.
-  if ((global as any)._playwrightRunCallback) {
-    (global as any)._playwrightRunCallback(playwrightRun());
-    return;
-  }
-  (global as any)._playwrightRun = playwrightRun;
-})();