Use puppeteer.launch instead of browser constructor (#255)

This patch: - split browser launching logic from Browser into `lib/Launcher.js` - introduce `puppeteer` namespace which currently has a single `launch` method to start a browser With this patch, the browser is no longer created with the `new Browser(..)` command. Instead, it should be "launched" via the `puppeteer.launch` method: ```js const puppeteer = require('puppeteer'); puppeteer.launch().then(async browser => { ... }); ``` With this approach browser instance lifetime matches the lifetime of actual browser process. This helps us: - remove proxy streams, e.g. browser.stderr and browser.stdout - cleanup browser class and make it possible to connect to remote browser - introduce events on the browser instance, e.g. 'page' event. In case of lazy-launching browser, we should've launch browser when an event listener is added, which is unneded comlpexity.
2017-08-14 18:08:06 -07:00 · 2017-08-14 18:08:06 -07:00 · 13e8580a34
commit 13e8580a34
parent 0a3dd4e727
19 changed files with 301 additions and 291 deletions
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@ -133,11 +133,11 @@ npm run coverage
 Puppeteer uses [DEBUG](https://github.com/visionmedia/debug) module to expose some of it's inner guts under the `puppeteer` namespace. Try putting the following in a file called `script.js` and running it via `DEBUG=* node script.js`:

 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

 (async() => {

+const browser = await puppeteer.launch();
 const page = await browser.newPage();
 await page.goto('https://example.com');
 browser.close();
--- a/README.md
+++ b/README.md
@ -39,10 +39,11 @@ of `Browser`, open pages, and then manipulate them with [Puppeteer's API](https:
 **Example** - navigating to https://example.com and saving a screenshot as *example.png*:

 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

 (async() => {
+
+const browser = await puppeteer.launch();
 const page = await browser.newPage();
 await page.goto('https://example.com');
 await page.screenshot({path: 'example.png'});
@ -54,16 +55,17 @@ browser.close();
 or, without `async`/`await`:

 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

-browser.newPage().then(page => {
-  page.goto('https://example.com').then(response => {
-     page.screenshot({path: 'example.png'}).then(buffer => {
-       browser.close();
-     });
+puppeteer.launch()
+  .then(browser => browser.newPage())
+  .then(page => {
+    page.goto('https://example.com').then(response => {
+       page.screenshot({path: 'example.png'}).then(buffer => {
+         browser.close();
+       });
+    });
  });
-});
 ```

 Puppeteer sets an initial page size to 800px x 600px, which defines the screenshot size. The page size can be customized  with [`Page.setViewport()`](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#pagesetviewportviewport).
@ -71,10 +73,11 @@ Puppeteer sets an initial page size to 800px x 600px, which defines the screensh
 **Example** - create a PDF.

 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

 (async() => {
+
+const browser = await puppeteer.launch();
 const page = await browser.newPage();
 await page.goto('https://news.ycombinator.com', {waitUntil: 'networkidle'});
 await page.pdf({path: 'hn.pdf', format: 'A4'});
@ -92,7 +95,7 @@ See [`Page.pdf()`](https://github.com/GoogleChrome/puppeteer/blob/master/docs/ap
 Puppeteer launches Chromium in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome). To launch a full version of Chromium, set the ['headless' option](https://github.com/GoogleChrome/puppeteer/blob/master/docs/api.md#new-browseroptions) when creating a browser:

 ```js
-const browser = new Browser({headless: false});
+const browser = await puppeteer.launch({headless: false});
 ```

 **2. Runs a bundled version of Chromium**
--- a/docs/api.md
+++ b/docs/api.md
@ -5,12 +5,11 @@
 <!-- toc -->

 - [Puppeteer](#puppeteer)
+  * [class: Puppeteer](#class-puppeteer)
+    + [puppeteer.launch([options])](#puppeteerlaunchoptions)
  * [class: Browser](#class-browser)
-    + [new Browser([options])](#new-browseroptions)
    + [browser.close()](#browserclose)
    + [browser.newPage()](#browsernewpage)
-    + [browser.stderr](#browserstderr)
-    + [browser.stdout](#browserstdout)
    + [browser.version()](#browserversion)
  * [class: Page](#class-page)
    + [event: 'console'](#event-console)
@ -120,18 +119,33 @@

 Puppeteer is a Node library which provides a high-level API to control Chromium over the DevTools Protocol.

-Puppeteer provides a top-level require which has a [Browser](#class-browser) class.
-The following is a typical example of using a Browser class to drive automation:
+
+### class: Puppeteer
+
+Puppeteer module provides a method to launch a chromium instance.
+The following is a typical example of using a Puppeteer to drive automation:
 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
-browser.newPage().then(async page => {
+const puppeteer = require('puppeteer');
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  await page.goto('https://google.com');
  // other actions...
  browser.close();
 });
 ```

+#### puppeteer.launch([options])
+- `options` <[Object]>  Set of configurable options to set on the browser. Can have the following fields:
+  - `ignoreHTTPSErrors` <[boolean]> Whether to ignore HTTPS errors during navigation. Defaults to `false`.
+  - `headless` <[boolean]> Whether to run chromium in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome). Defaults to `true`.
+  - `executablePath` <[string]> Path to a chromium executable to run instead of bundled chromium. If `executablePath` is a relative path, then it is resolved relative to [current working directory](https://nodejs.org/api/process.html#process_process_cwd).
+  - `slowMo` <[number]> Slows down Puppeteer operations by the specified amount of milliseconds. Useful so that you can see what is going on.
+  - `args` <[Array]<[string]>> Additional arguments to pass to the chromium instance. List of chromium flags can be found [here](http://peter.sh/experiments/chromium-command-line-switches/).
+  - `dumpio` <[boolean]> Whether to pipe browser process stdout and stderr into `process.stdout` and `process.stderr`. Defaults to `false`.
+- returns: <[Promise]<[Browser]>> Promise which resolves to browser instance.
+
+The method launches a browser instance with given arguments. The browser will be closed when the parent node.js process gets closed.
+
 ### class: Browser

 Browser manages a browser instance, creating it with a predefined
@ -140,23 +154,15 @@ not necessarily result in launching browser; the instance will be launched when

 A typical scenario of using [Browser] is opening a new page and navigating it to a desired URL:
 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
-browser.newPage().then(async page => {
+const puppeteer = require('puppeteer');
+
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  await page.goto('https://example.com');
  browser.close();
 });
 ```

-#### new Browser([options])
- `options` <[Object]>  Set of configurable options to set on the browser. Can have the following fields:
-  - `ignoreHTTPSErrors` <[boolean]> Whether to ignore HTTPS errors during navigation. Defaults to `false`.
-  - `headless` <[boolean]> Whether to run chromium in [headless mode](https://developers.google.com/web/updates/2017/04/headless-chrome). Defaults to `true`.
-  - `executablePath` <[string]> Path to a chromium executable to run instead of bundled chromium. If `executablePath` is a relative path, then it is resolved relative to [current working directory](https://nodejs.org/api/process.html#process_process_cwd).
-  - `slowMo` <[number]> Slows down Puppeteer operations by the specified amount of milliseconds. Useful
-so that you can see what is going on.
-  - `args` <[Array]<[string]>> Additional arguments to pass to the chromium instance. List of chromium flags can be found [here](http://peter.sh/experiments/chromium-command-line-switches/).
-

 #### browser.close()

@ -166,36 +172,6 @@ Closes browser with all the pages (if any were opened). The browser object itsel
 - returns: <[Promise]<[Page]>> Promise which resolves to a new [Page] object.


-#### browser.stderr
- <[stream.Readable]>
-
-A Readable Stream that represents the browser process's stderr.
-For example, `stderr` could be piped into `process.stderr`:
-```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
-browser.stderr.pipe(process.stderr);
-browser.version().then(version => {
-  console.log(version);
-  browser.close();
-});
-```
-
-#### browser.stdout
- <[stream.Readable]>
-
-A Readable Stream that represents the browser process's stdout.
-For example, `stdout` could be piped into `process.stdout`:
-```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
-browser.stdout.pipe(process.stdout);
-browser.version().then(version => {
-  console.log(version);
-  browser.close();
-});
-```
-
 #### browser.version()
 - returns: <[Promise]<[string]>> String describing browser version. For headless chromium, this is similar to `HeadlessChrome/61.0.3153.0`. For non-headless, this is `Chrome/61.0.3153.0`.

@ -207,9 +183,10 @@ Page provides methods to interact with browser page. Page could be thought about

 An example of creating a page, navigating it to a URL and saving screenshot as `screenshot.png`:
 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
-browser.newPage().then(async page =>
+const puppeteer = require('puppeteer');
+
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  await page.goto('https://example.com');
  await page.screenshot({path: 'screenshot.png'});
  browser.close();
@ -298,11 +275,11 @@ If the `puppeteerFunction` returns a promise, it would be awaited.

 An example of adding `window.md5` binding to the page:
 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');
 const crypto = require('crypto');

-browser.newPage().then(async page => {
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  page.on('console', console.log);
  await page.setInPageCallback('md5', text => crypto.createHash('md5').update(text).digest('hex'));
  await page.evaluate(async () => {
@ -318,11 +295,11 @@ browser.newPage().then(async page => {
 An example of adding `window.readfile` binding to the page:

 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');
 const fs = require('fs');

-browser.newPage().then(async page => {
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  page.on('console', console.log);
  await page.setInPageCallback('readfile', async filePath => {
    return new Promise((resolve, reject) => {
@ -380,11 +357,12 @@ Emulates given device metrics and user agent. This method is a shortcut for call
 To aid emulation, puppeteer provides a list of device descriptors which could be obtained via the `require('puppeteer/DeviceDescriptors')` command.
 Below is an example of emulating iPhone 6 in puppeteer:
 ```js
-const {Browser} = require('puppeteer');
+const puppeteer = require('puppeteer');
 const devices = require('puppeteer/DeviceDescriptors');
 const iPhone = devices['iPhone 6'];
-const browser = new Browser();
-browser.newPage().then(async page => {
+
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  await page.emulate(iPhone);
  await page.goto('https://google.com');
  // other actions...
@ -402,9 +380,9 @@ List of all available devices is available in the source code: [DeviceDescriptor
 If the function, passed to the `page.evaluate`, returns a [Promise], then `page.evaluate` would wait for the promise to resolve and return it's value.

 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
-browser.newPage().then(async page =>
+const puppeteer = require('puppeteer');
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  const result = await page.evaluate(() => {
    return Promise.resolve(8 * 7);
  });
@ -613,10 +591,9 @@ Activating request interception enables  `request.abort` and `request.continue`.

 An example of a naïve request interceptor which aborts all image requests:
 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
-
-browser.newPage().then(async page =>
+const puppeteer = require('puppeteer');
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  await page.setRequestInterceptionEnabled(true);
  page.on('request', request => {
    if (interceptedRequest.url.endsWith('.png') || interceptedRequest.url.endsWith('.jpg'))
@ -713,10 +690,9 @@ Shortcut for [page.mainFrame().waitFor(selectorOrFunctionOrTimeout[, options])](

 The `waitForFunction` could be used to observe viewport size change:
 ```js
-const {Browser} = require('.');
-const browser = new Browser();
-
-browser.newPage().then(async page => {
+const puppeteer = require('puppeteer');
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  const watchDog = page.waitForFunction('window.innerWidth < 100');
  page.setViewport({width: 50, height: 50});
  await watchDog;
@ -748,10 +724,9 @@ immediately. If the selector doesn't appear after the `timeout` milliseconds of

 This method works across navigations:
 ```js
-const {Browser} = new require('puppeteer');
-const browser = new Browser();
-
-browser.newPage().then(async page => {
+const puppeteer = require('puppeteer');
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  let currentURL;
  page.waitForSelector('img').then(() => console.log('First URL with image: ' + currentURL));
  for (currentURL of ['https://example.com', 'https://google.com', 'https://bbc.com'])
@ -874,9 +849,10 @@ Only one trace can be active at a time per browser.

 An example of using `Dialog` class:
 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser({headless: false});
-browser.newPage().then(async page => {
+const puppeteer = require('puppeteer');
+
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  page.on('dialog', dialog => {
    console.log(dialog.message());
    dialog.dismiss();
@ -916,10 +892,10 @@ At every point of time, page exposes its current frame tree via the [page.mainFr
 An example of dumping frame tree:

 ```js
-const {Browser} = new require('.');
-const browser = new Browser({headless: true});
+const puppeteer = require('puppeteer');

-browser.newPage().then(async page => {
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  await page.goto('https://www.google.com/chrome/browser/canary.html');
  dumpFrameTree(page.mainFrame(), '');
  browser.close();
@ -958,9 +934,10 @@ Adds a `<script>` tag to the frame with the desired url. Alternatively, JavaScri
 If the function, passed to the `page.evaluate`, returns a [Promise], then `page.evaluate` would wait for the promise to resolve and return it's value.

 ```js
-const {Browser} = require('puppeteer');
-const browser = new Browser();
-browser.newPage().then(async page =>
+const puppeteer = require('puppeteer');
+
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  const result = await page.evaluate(() => {
    return Promise.resolve(8 * 7);
  });
@ -1042,10 +1019,10 @@ This method behaves differently with respect to the type of the first parameter:

 The `waitForFunction` could be used to observe viewport size change:
 ```js
-const {Browser} = require('.');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

-browser.newPage().then(async page => {
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  const watchDog = page.waitForFunction('window.innerWidth < 100');
  page.setViewport({width: 50, height: 50});
  await watchDog;
@ -1066,10 +1043,10 @@ immediately. If the selector doesn't appear after the `timeout` milliseconds of

 This method works across navigations:
 ```js
-const {Browser} = new require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

-browser.newPage().then(async page => {
+puppeteer.launch().then(async browser => {
+  let page = await browser.newPage();
  let currentURL;
  page.waitForSelector('img').then(() => console.log('First URL with image: ' + currentURL));
  for (currentURL of ['https://example.com', 'https://google.com', 'https://bbc.com'])
--- a/examples/block-images.js
+++ b/examples/block-images.js
@ -14,13 +14,14 @@
 * limitations under the License.
 */

-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

 (async() => {

+const browser = await puppeteer.launch();
 const page = await browser.newPage();
-await page.setRequestInterceptor(request => {
+await page.setRequestInterceptionEnabled(true);
+page.on('request', request => {
  if (/\.(png|jpg|jpeg$)/.test(request.url))
    request.abort();
  else
--- a/examples/detect-sniff.js
+++ b/examples/detect-sniff.js
@ -14,8 +14,7 @@
 * limitations under the License.
 */

-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

 function sniffDetector() {
  let userAgent = window.navigator.userAgent;
@ -34,6 +33,7 @@ function sniffDetector() {

 (async() => {

+const browser = await puppeteer.launch();
 const page = await browser.newPage();
 await page.evaluateOnNewDocument(sniffDetector);
 await page.goto('https://www.google.com', {waitUntil: 'networkidle'});
@ -41,4 +41,4 @@ console.log('Sniffed: ' + (await page.evaluate(() => !!navigator.sniffed)));

 browser.close();

-})();
+})();
--- a/examples/pdf.js
+++ b/examples/pdf.js
@ -14,11 +14,11 @@
 * limitations under the License.
 */

-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

 (async() => {

+const browser = await puppeteer.launch();
 const page = await browser.newPage();
 await page.goto('https://news.ycombinator.com', {waitUntil: 'networkidle'});
 // page.pdf() is currently supported only in headless mode.
--- a/examples/screenshot-fullpage.js
+++ b/examples/screenshot-fullpage.js
@ -14,12 +14,12 @@
 * limitations under the License.
 */

-const {Browser} = require('puppeteer');
+const puppeteer = require('puppeteer');
 const devices = require('puppeteer/DeviceDescriptors');
-const browser = new Browser();

 (async() => {

+const browser = await puppeteer.launch();
 let page = await browser.newPage();
 await page.emulate(devices['iPhone 6']);
 await page.goto('https://www.nytimes.com/');
--- a/examples/screenshot.js
+++ b/examples/screenshot.js
@ -14,11 +14,11 @@
 * limitations under the License.
 */

-const {Browser} = require('puppeteer');
-const browser = new Browser();
+const puppeteer = require('puppeteer');

 (async() => {

+const browser = await puppeteer.launch();
 const page = await browser.newPage();
 await page.goto('http://example.com');
 await page.screenshot({path: 'example.png'});
--- a/examples/search.js
+++ b/examples/search.js
@ -14,11 +14,11 @@
 * limitations under the License.
 */

+const puppeteer = require('puppeteer');
+
 (async() => {

-const {Browser} = require('puppeteer');
-const browser = new Browser();
-
+const browser = await puppeteer.launch();
 const page = await browser.newPage();
 await page.goto('https://google.com', {waitUntil: 'networkidle'});
 // Type our query into the search bar
--- a/index.js
+++ b/index.js
@ -14,6 +14,4 @@
 * limitations under the License.
 */

-module.exports = {
-  Browser: require('./lib/Browser')
-};
+module.exports = require('./lib/Puppeteer');
--- a/lib/Browser.js
+++ b/lib/Browser.js
@ -14,85 +14,26 @@
 * limitations under the License.
 */

-const {Duplex} = require('stream');
-const path = require('path');
 const helper = require('./helper');
-const removeRecursive = require('rimraf').sync;
 const Page = require('./Page');
-const childProcess = require('child_process');
-const Downloader = require('../utils/ChromiumDownloader');
-const Connection = require('./Connection');
-const readline = require('readline');
-
-const CHROME_PROFILE_PATH = path.resolve(__dirname, '..', '.dev_profile');
-let browserId = 0;
-
-const DEFAULT_ARGS = [
-  '--disable-background-networking',
-  '--disable-background-timer-throttling',
-  '--disable-client-side-phishing-detection',
-  '--disable-default-apps',
-  '--disable-hang-monitor',
-  '--disable-popup-blocking',
-  '--disable-prompt-on-repost',
-  '--disable-sync',
-  '--enable-automation',
-  '--metrics-recording-only',
-  '--no-first-run',
-  '--password-store=basic',
-  '--remote-debugging-port=0',
-  '--safebrowsing-disable-auto-update',
-  '--use-mock-keychain',
-];

 class Browser {
  /**
-   * @param {!Object=} options
+   * @param {!Connection} connection
+   * @param {boolean} ignoreHTTPSErrors
+   * @param {function()=} closeCallback
   */
-  constructor(options) {
-    options = options || {};
-    ++browserId;
-    this._userDataDir = CHROME_PROFILE_PATH + browserId;
-    this._remoteDebuggingPort = 0;
-    this._chromeArguments = DEFAULT_ARGS.concat([
-      `--user-data-dir=${this._userDataDir}`,
-    ]);
-    if (typeof options.headless !== 'boolean' || options.headless) {
-      this._chromeArguments.push(
-          `--headless`,
-          `--disable-gpu`,
-          `--hide-scrollbars`
-      );
-    }
-    if (typeof options.executablePath === 'string') {
-      this._chromeExecutable = options.executablePath;
-    } else {
-      let chromiumRevision = require('../package.json').puppeteer.chromium_revision;
-      let revisionInfo = Downloader.revisionInfo(Downloader.currentPlatform(), chromiumRevision);
-      console.assert(revisionInfo, 'Chromium revision is not downloaded. Run npm install');
-      this._chromeExecutable = revisionInfo.executablePath;
-    }
-    this._ignoreHTTPSErrors = !!options.ignoreHTTPSErrors;
-    if (Array.isArray(options.args))
-      this._chromeArguments.push(...options.args);
-    this._connectionDelay = options.slowMo || 0;
-    this._terminated = false;
-    this._chromeProcess = null;
-    this._launchPromise = null;
+  constructor(connection, ignoreHTTPSErrors, closeCallback) {
+    this._ignoreHTTPSErrors = ignoreHTTPSErrors;
    this._screenshotTaskQueue = new TaskQueue();
-
-    this.stderr = new ProxyStream();
-    this.stdout = new ProxyStream();
+    this._connection = connection;
+    this._closeCallback = closeCallback || new Function();
  }

  /**
   * @return {!Promise<!Page>}
   */
  async newPage() {
-    await this._ensureChromeIsRunning();
-    if (!this._chromeProcess || this._terminated)
-      throw new Error('ERROR: this chrome instance is not alive any more!');
-
    const {targetId} = await this._connection.send('Target.createTarget', {url: 'about:blank'});
    const client = await this._connection.createSession(targetId);
    return await Page.create(client, this._ignoreHTTPSErrors, this._screenshotTaskQueue);
@ -102,84 +43,19 @@ class Browser {
   * @return {!Promise<string>}
   */
  async version() {
-    await this._ensureChromeIsRunning();
    let version = await this._connection.send('Browser.getVersion');
    return version.product;
  }

-  /**
-   * @return {!Promise}
-   */
-  async _ensureChromeIsRunning() {
-    if (!this._launchPromise)
-      this._launchPromise = this._launchChrome();
-    return this._launchPromise;
-  }
-
-  /**
-   * @return {!Promise}
-   */
-  async _launchChrome() {
-    this._chromeProcess = childProcess.spawn(this._chromeExecutable, this._chromeArguments, {});
-    let stderr = '';
-    this._chromeProcess.stderr.on('data', data => stderr += data.toString('utf8'));
-    // Cleanup as processes exit.
-    const onProcessExit = () => this._chromeProcess.kill();
-    process.on('exit', onProcessExit);
-    this._chromeProcess.on('exit', () => {
-      this._terminated = true;
-      process.removeListener('exit', onProcessExit);
-      removeRecursive(this._userDataDir);
-    });
-    this._chromeProcess.stderr.pipe(this.stderr);
-    this._chromeProcess.stdout.pipe(this.stdout);
-
-    let {port, browserTargetId} = await waitForRemoteDebuggingPort(this._chromeProcess);
-    // Failed to connect to browser.
-    if (port === -1) {
-      this._chromeProcess.kill();
-      throw new Error('Failed to connect to chrome!');
-    }
-
-    if (this._terminated)
-      throw new Error('Failed to launch chrome! ' + stderr);
-    this._remoteDebuggingPort = port;
-    this._connection = await Connection.create(port, browserTargetId, this._connectionDelay);
-  }
-
  close() {
-    if (!this._chromeProcess)
-      return;
-    this._chromeProcess.kill();
+    this._connection.dispose();
+    this._closeCallback.call(null);
  }
 }

 module.exports = Browser;
 helper.tracePublicAPI(Browser);

-/**
- * @param {!ChildProcess} chromeProcess
- * @return {!Promise<number>}
- */
-function waitForRemoteDebuggingPort(chromeProcess) {
-  return new Promise(fulfill => {
-    const rl = readline.createInterface({ input: chromeProcess.stderr });
-    rl.on('line', onLine);
-    rl.once('close', () => fulfill(-1));
-
-    /**
-     * @param {string} line
-     */
-    function onLine(line) {
-      const match = line.match(/^DevTools listening on .*:(\d+)(\/.*)$/);
-      if (!match)
-        return;
-      rl.removeListener('line', onLine);
-      fulfill({port: Number.parseInt(match[1], 10), browserTargetId: match[2]});
-    }
-  });
-}
-
 class TaskQueue {
  constructor() {
    this._chain = Promise.resolve();
@ -195,17 +71,3 @@ class TaskQueue {
    return result;
  }
 }
-
-class ProxyStream extends Duplex {
-  _read() { }
-
-  /**
-   * @param {?} chunk
-   * @param {string} encoding
-   * @param {function()} callback
-   */
-  _write(chunk, encoding, callback) {
-    this.push(chunk, encoding);
-    callback();
-  }
-}
--- a/lib/Connection.js
+++ b/lib/Connection.js
@ -99,7 +99,8 @@ class Connection extends EventEmitter {
  /**
   * @return {!Promise}
   */
-  async dispose() {
+  dispose() {
+    this._onClose();
    this._ws.close();
  }

--- a/lib/Launcher.js
+++ b/lib/Launcher.js
@ -0,0 +1,128 @@
+/**
+ * Copyright 2017 Google Inc. All rights reserved.
+ *
+ * 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.
+ */
+const path = require('path');
+const removeRecursive = require('rimraf').sync;
+const childProcess = require('child_process');
+const Downloader = require('../utils/ChromiumDownloader');
+const Connection = require('./Connection');
+const Browser = require('./Browser');
+const readline = require('readline');
+
+const CHROME_PROFILE_PATH = path.resolve(__dirname, '..', '.dev_profile');
+let browserId = 0;
+
+const DEFAULT_ARGS = [
+  '--disable-background-networking',
+  '--disable-background-timer-throttling',
+  '--disable-client-side-phishing-detection',
+  '--disable-default-apps',
+  '--disable-hang-monitor',
+  '--disable-popup-blocking',
+  '--disable-prompt-on-repost',
+  '--disable-sync',
+  '--enable-automation',
+  '--metrics-recording-only',
+  '--no-first-run',
+  '--password-store=basic',
+  '--remote-debugging-port=0',
+  '--safebrowsing-disable-auto-update',
+  '--use-mock-keychain',
+];
+
+class Launcher {
+  /**
+   * @param {!Object} options
+   * @return {!Promise<!Browser>}
+   */
+  static async launch(options) {
+    options = options || {};
+    ++browserId;
+    let userDataDir = CHROME_PROFILE_PATH + browserId;
+    let chromeArguments = DEFAULT_ARGS.concat([
+      `--user-data-dir=${userDataDir}`,
+    ]);
+    if (typeof options.headless !== 'boolean' || options.headless) {
+      chromeArguments.push(
+          `--headless`,
+          `--disable-gpu`,
+          `--hide-scrollbars`
+      );
+    }
+    let chromeExecutable = options.executablePath;
+    if (typeof chromeExecutable !== 'string') {
+      let chromiumRevision = require('../package.json').puppeteer.chromium_revision;
+      let revisionInfo = Downloader.revisionInfo(Downloader.currentPlatform(), chromiumRevision);
+      console.assert(revisionInfo, 'Chromium revision is not downloaded. Run npm install');
+      chromeExecutable = revisionInfo.executablePath;
+    }
+    if (Array.isArray(options.args))
+      chromeArguments.push(...options.args);
+    let chromeProcess = childProcess.spawn(chromeExecutable, chromeArguments, {});
+    if (options.dumpio) {
+      chromeProcess.stdout.pipe(process.stdout);
+      chromeProcess.stderr.pipe(process.stderr);
+    }
+    let stderr = '';
+    chromeProcess.stderr.on('data', data => stderr += data.toString('utf8'));
+    // Cleanup as processes exit.
+    const onProcessExit = () => chromeProcess.kill();
+    process.on('exit', onProcessExit);
+    let terminated = false;
+    chromeProcess.on('exit', () => {
+      terminated = true;
+      process.removeListener('exit', onProcessExit);
+      removeRecursive(userDataDir);
+    });
+
+    let {port, browserTargetId} = await waitForRemoteDebuggingPort(chromeProcess);
+    if (terminated)
+      throw new Error('Failed to launch chrome! ' + stderr);
+    // Failed to connect to browser.
+    if (port === -1) {
+      chromeProcess.kill();
+      throw new Error('Failed to connect to chrome!');
+    }
+
+    let connectionDelay = options.slowMo || 0;
+    let connection = await Connection.create(port, browserTargetId, connectionDelay);
+    return new Browser(connection, !!options.ignoreHTTPSErrors, () => chromeProcess.kill());
+  }
+}
+
+/**
+ * @param {!ChildProcess} chromeProcess
+ * @return {!Promise<number>}
+ */
+function waitForRemoteDebuggingPort(chromeProcess) {
+  return new Promise(fulfill => {
+    const rl = readline.createInterface({ input: chromeProcess.stderr });
+    rl.on('line', onLine);
+    rl.once('close', () => fulfill(-1));
+
+    /**
+     * @param {string} line
+     */
+    function onLine(line) {
+      const match = line.match(/^DevTools listening on .*:(\d+)(\/.*)$/);
+      if (!match)
+        return;
+      rl.removeListener('line', onLine);
+      fulfill({port: Number.parseInt(match[1], 10), browserTargetId: match[2]});
+    }
+  });
+}
+
+module.exports = Launcher;
--- a/lib/Puppeteer.js
+++ b/lib/Puppeteer.js
@ -0,0 +1,30 @@
+/**
+ * Copyright 2017 Google Inc. All rights reserved.
+ *
+ * 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.
+ */
+const helper = require('./helper');
+const Launcher = require('./Launcher');
+
+class Puppeteer {
+  /**
+   * @param {!Object=} options
+   * @return {!Promise<!Browser>}
+   */
+  static async launch(options) {
+    return Launcher.launch(options);
+  }
+}
+
+module.exports = Puppeteer;
+helper.tracePublicAPI(Puppeteer);
--- a/phantom_shim/runner.js
+++ b/phantom_shim/runner.js
@ -15,6 +15,7 @@
 * limitations under the License.
 */

+const await = require('./utilities').await;
 const vm = require('vm');
 const path = require('path');
 const fs = require('fs');
@ -24,7 +25,7 @@ const System = require('./System');
 const WebPage = require('./WebPage');
 const WebServer = require('./WebServer');
 const child_process = require('child_process');
-const Browser = require('..').Browser;
+const puppeteer = require('..');
 const argv = require('minimist')(process.argv.slice(2), {
  alias: { v: 'version' },
  boolean: ['headless'],
@ -55,23 +56,19 @@ if (!fs.existsSync(scriptPath)) {
  return;
 }

-let browser = new Browser({
-  headless: argv.headless,
-  args: ['--no-sandbox']
-});
-
-let context = createPhantomContext(browser, scriptPath, argv);
+let context = createPhantomContext(argv.headless, scriptPath, argv);
 let scriptContent = fs.readFileSync(scriptPath, 'utf8');
 vm.runInContext(scriptContent, context);

 /**
- * @param {!Browser} browser
+ * @param {boolean} headless
 * @param {string} scriptPath
 * @param {!Array<string>} argv
 * @return {!Object}
 */
-function createPhantomContext(browser, scriptPath, argv) {
+function createPhantomContext(headless, scriptPath, argv) {
  let context = {};
+  let browser = null;
  context.setInterval = setInterval;
  context.setTimeout = setTimeout;
  context.clearInterval = clearInterval;
@ -80,7 +77,7 @@ function createPhantomContext(browser, scriptPath, argv) {
  context.phantom = Phantom.create(context, scriptPath);
  context.console = console;
  context.window = context;
-  context.WebPage = options => new WebPage(browser, scriptPath, options);
+  context.WebPage = options => new WebPage(ensureBrowser(), scriptPath, options);

  vm.createContext(context);

@ -104,5 +101,15 @@ function createPhantomContext(browser, scriptPath, argv) {
    filename: 'bootstrap.js'
  })(nativeExports);
  return context;
+
+  function ensureBrowser() {
+    if (!browser) {
+      browser = await(puppeteer.launch({
+        headless: argv.headless,
+        args: ['--no-sandbox']
+      }));
+    }
+    return browser;
+  }
 }

--- a/test/test.js
+++ b/test/test.js
@ -20,7 +20,7 @@ const path = require('path');
 const helper = require('../lib/helper');
 if (process.env.COVERAGE)
  helper.recordPublicAPICoverage();
-const Browser = require('../lib/Browser');
+const puppeteer = require('..');
 const SimpleServer = require('./server/SimpleServer');
 const GoldenUtils = require('./golden-utils');

@ -82,7 +82,7 @@ afterAll(SX(async function() {
 describe('Browser', function() {
  it('Browser.Options.ignoreHTTPSErrors', SX(async function() {
    let options = Object.assign({ignoreHTTPSErrors: true}, defaultBrowserOptions);
-    let browser = new Browser(options);
+    let browser = await puppeteer.launch(options);
    let page = await browser.newPage();
    let error = null;
    let response = null;
@ -96,7 +96,7 @@ describe('Browser', function() {
    browser.close();
  }));
  it('should reject all promises when browser is closed', SX(async function() {
-    let browser = new Browser(defaultBrowserOptions);
+    let browser = await puppeteer.launch(defaultBrowserOptions);
    let page = await browser.newPage();
    let error = null;
    let neverResolves = page.evaluate(() => new Promise(r => {})).catch(e => error = e);
@ -114,7 +114,7 @@ describe('Page', function() {
  let page;

  beforeAll(SX(async function() {
-    browser = new Browser(defaultBrowserOptions);
+    browser = await puppeteer.launch(defaultBrowserOptions);
  }));

  afterAll(SX(async function() {
--- a/utils/doclint/check_public_api/index.js
+++ b/utils/doclint/check_public_api/index.js
@ -24,6 +24,7 @@ const EXCLUDE_CLASSES = new Set([
  'EmulationManager',
  'FrameManager',
  'Helper',
+  'Launcher',
  'Multimap',
  'NavigatorWatcher',
  'NetworkManager',
@ -35,6 +36,7 @@ const EXCLUDE_CLASSES = new Set([

 const EXCLUDE_METHODS = new Set([
  'Body.constructor',
+  'Browser.constructor',
  'Dialog.constructor',
  'Frame.constructor',
  'Headers.constructor',
--- a/utils/doclint/check_public_api/test/test.js
+++ b/utils/doclint/check_public_api/test/test.js
@ -17,7 +17,7 @@
 const fs = require('fs');
 const rm = require('rimraf').sync;
 const path = require('path');
-const Browser = require('../../../../lib/Browser');
+const puppeteer = require('../../../..');
 const checkPublicAPI = require('..');
 const SourceFactory = require('../../SourceFactory');
 const GoldenUtils = require('../../../../test/golden-utils');
@ -25,7 +25,7 @@ const GoldenUtils = require('../../../../test/golden-utils');
 const OUTPUT_DIR = path.join(__dirname, 'output');
 const GOLDEN_DIR = path.join(__dirname, 'golden');

-const browser = new Browser({args: ['--no-sandbox']});
+let browser;
 let page;
 let specName;

@ -34,6 +34,7 @@ jasmine.getEnv().addReporter({
 });

 beforeAll(SX(async function() {
+  browser = await puppeteer.launch({args: ['--no-sandbox']});
  page = await browser.newPage();
  if (fs.existsSync(OUTPUT_DIR))
    rm(OUTPUT_DIR);
--- a/utils/doclint/cli.js
+++ b/utils/doclint/cli.js
@ -15,7 +15,7 @@
 * limitations under the License.
 */

-const Browser = require('../../lib/Browser');
+const puppeteer = require('../..');
 const path = require('path');
 const SourceFactory = require('./SourceFactory');

@ -44,7 +44,7 @@ async function run() {
    const preprocessor = require('./preprocessor');
    messages.push(...await preprocessor(mdSources));

-    const browser = new Browser({args: ['--no-sandbox']});
+    const browser = await puppeteer.launch({args: ['--no-sandbox']});
    const page = await browser.newPage();
    const checkPublicAPI = require('./check_public_api');
    const jsSources = await sourceFactory.readdir(path.join(PROJECT_DIR, 'lib'), '.js');