How to take a screenshot of the entire web page (full-page screenshot), not only partial (top-to-bottom) using Selenium WebDriver?

My code: (Java bindings)

System.setProperty("webdriver.chrome.driver","/home/alex/Downloads/chromedriver_linux64/chromedriver");
WebDriver driver = new ChromeDriver();
driver.get("http://google.com");
File scrFile = ((TakesScreenshot)driver).getScreenshotAs(OutputType.FILE);
FileUtils.copyFile(scrFile, new File(RESULT_FILENAME));

Any ideas on how to tackle this?