title: How can I set the browser window size when using `google-chrome --headless`?
body: <p>I tried setting the browser size on Chrome <code>--headless</code> by using Selenium WebDriver commands.</p>
  <p>I get this WebDriver error:</p>
  <pre><code>      - Failed: unknown error: cannot get automation extension
  from unknown error: page could not be found: chrome-extension://aapnijgdinlhnhlmodcfapnahmbfebeb/_generated_background_page.html
    (Session info: headless chrome=58.0.3029.81)
    (Driver info: chromedriver=2.29.461571 (8a88bbe0775e2a23afda0ceaf2ef7ee74e822cc5),platform=Linux 4.4.0-72-generic x86_64) (WARNING: The server did not provide any stacktrace information)
  Command duration or timeout: 10.07 seconds
  Build info: version: '3.3.1', revision: '5234b32', time: '2017-03-10 09:04:52 -0800'
  System info: host: '826f6a766112', ip: '172.17.0.2', os.name: 'Linux', os.arch: 'amd64', os.version: '4.4.0-72-generic', java.version: '1.8.0_121'
  Driver info: org.openqa.selenium.chrome.ChromeDriver
  Capabilities [{applicationCacheEnabled=false, rotatable=false, mobileEmulationEnabled=false, networkConnectionEnabled=false, chrome={chromedriverVersion=2.29.461571 (8a88bbe0775e2a23afda0ceaf2ef7ee74e822cc5), userDataDir=/tmp/.org.chromium.Chromium.cuymDL}, takesHeapSnapshot=true, pageLoadStrategy=normal, databaseEnabled=false, handlesAlerts=true, hasTouchScreen=false, version=58.0.3029.81, platform=LINUX, browserConnectionEnabled=false, nativeEvents=true, acceptSslCerts=true, locationContextEnabled=true, webStorageEnabled=true, browserName=chrome, takesScreenshot=true, javascriptEnabled=true, cssSelectorsEnabled=true, unexpectedAlertBehaviour=}]
  Session ID: 9569e5ebd8f7540ce510b20647443baf
  </code></pre>