diff --git a/src/chromium/crBrowser.ts b/src/chromium/crBrowser.ts
index 14ed5b313c..b461a5d35f 100644
--- a/src/chromium/crBrowser.ts
+++ b/src/chromium/crBrowser.ts
@@ -46,9 +46,9 @@ export class CRBrowser extends BrowserBase {
   private _tracingClient: CRSession | undefined;
   readonly _isHeadful: boolean;
 
-  static async connect(transport: ConnectionTransport, isPersistent: boolean, logger: InnerLogger, options: { slowMo?: number, headless?: boolean } = {}): Promise<CRBrowser> {
+  static async connect(transport: ConnectionTransport, isPersistent: boolean, logger: InnerLogger, options: { slowMo?: number, headless?: boolean, viewport?: types.Size | null } = {}): Promise<CRBrowser> {
     const connection = new CRConnection(SlowMoTransport.wrap(transport, options.slowMo), logger);
-    const browser = new CRBrowser(connection, logger, isPersistent, !options.headless);
+    const browser = new CRBrowser(connection, logger, { persistent: isPersistent, headful: !options.headless, viewport: options.viewport });
     const session = connection.rootSession;
     if (!isPersistent) {
       await session.send('Target.setAutoAttach', { autoAttach: true, waitForDebuggerOnStart: true, flatten: true });
@@ -83,14 +83,14 @@ export class CRBrowser extends BrowserBase {
     return browser;
   }
 
-  constructor(connection: CRConnection, logger: InnerLogger, isPersistent: boolean, isHeadful: boolean) {
+  constructor(connection: CRConnection, logger: InnerLogger, options: { headful?: boolean, persistent?: boolean, viewport?: types.Size | null } = {}) {
     super(logger);
     this._connection = connection;
     this._session = this._connection.rootSession;
 
-    if (isPersistent)
-      this._defaultContext = new CRBrowserContext(this, null, validateBrowserContextOptions({}));
-    this._isHeadful = isHeadful;
+    if (options.persistent)
+      this._defaultContext = new CRBrowserContext(this, null, validateBrowserContextOptions({ viewport: options.viewport }));
+    this._isHeadful = !!options.headful;
     this._connection.on(ConnectionEvents.Disconnected, () => {
       for (const context of this._contexts.values())
         context._browserClosed();
diff --git a/src/chromium/crPage.ts b/src/chromium/crPage.ts
index 84bc024a47..820644a388 100644
--- a/src/chromium/crPage.ts
+++ b/src/chromium/crPage.ts
@@ -375,7 +375,7 @@ class FrameSession {
   }
 
   async _initialize(hasUIWindow: boolean) {
-    if (hasUIWindow) {
+    if (hasUIWindow && this._crPage._browserContext._options.viewport !== null) {
       const { windowId } = await this._client.send('Browser.getWindowForTarget');
       this._windowId = windowId;
     }
diff --git a/src/install/installer.ts b/src/install/installer.ts
index 67ee570289..0ecede3ceb 100644
--- a/src/install/installer.ts
+++ b/src/install/installer.ts
@@ -70,7 +70,7 @@ async function validateCache(packagePath: string, browsersPath: string, linksDir
   }
 
   // 3. Install missing browsers for this package.
-  const myBrowsers = JSON.parse((await fsReadFileAsync(path.join(packagePath, 'browsers.json'))).toString())['browsers'];
+  const myBrowsers = JSON.parse((await fsReadFileAsync(path.join(packagePath, 'browsers.json'))).toString())['browsers'] as browserPaths.BrowserDescriptor[];
   for (const browser of myBrowsers) {
     const browserPath = browserPaths.browserDirectory(browsersPath, browser);
     await browserFetcher.downloadBrowserWithProgressBar(browserPath, browser);
diff --git a/src/server/processLauncher.ts b/src/server/processLauncher.ts
index 3c5101744a..6bb64fec84 100644
--- a/src/server/processLauncher.ts
+++ b/src/server/processLauncher.ts
@@ -56,6 +56,9 @@ export type LaunchProcessOptions = {
   pipe?: boolean,
   tempDir?: string,
 
+  cwd?: string,
+  omitDownloads?: boolean,
+
   // Note: attemptToGracefullyClose should reject if it does not close the browser.
   attemptToGracefullyClose: () => Promise<any>,
   onkill: (exitCode: number | null, signal: string | null) => void,
@@ -81,7 +84,8 @@ export async function launchProcess(options: LaunchProcessOptions): Promise<Laun
         // @see https://nodejs.org/api/child_process.html#child_process_options_detached
         detached: process.platform !== 'win32',
         env: (options.env as {[key: string]: string}),
-        stdio
+        cwd: options.cwd,
+        stdio,
       }
   );
   if (!spawnedProcess.pid) {
@@ -104,7 +108,7 @@ export async function launchProcess(options: LaunchProcessOptions): Promise<Laun
     logger._log(browserStdErrLog, data);
   });
 
-  const downloadsPath = await mkdtempAsync(DOWNLOADS_FOLDER);
+  const downloadsPath = options.omitDownloads ? '' : await mkdtempAsync(DOWNLOADS_FOLDER);
 
   let processClosed = false;
   const waitForProcessToClose = new Promise((fulfill, reject) => {
@@ -115,7 +119,7 @@ export async function launchProcess(options: LaunchProcessOptions): Promise<Laun
       options.onkill(exitCode, signal);
       // Cleanup as processes exit.
       Promise.all([
-        removeFolderAsync(downloadsPath),
+        options.omitDownloads ? Promise.resolve() : removeFolderAsync(downloadsPath),
         options.tempDir ? removeFolderAsync(options.tempDir) : Promise.resolve()
       ]).catch((err: Error) => console.error(err)).then(fulfill);
     });