Adding an option to run Chrome headless

Author: barancev

java/client/src/org/openqa/selenium/chrome/ChromeOptions.java

@@ -214,6 +214,15 @@ public ChromeOptions setUnhandledPromptBehaviour(UnexpectedAlertBehaviour behavi
     return this;
   }
 
+  public ChromeOptions setHeadless(boolean headless) {
+    args.remove("--headless");
+    if (headless) {
+      args.add("--headless");
+      args.add("--disable-gpu");
+    }
+    return this;
+  }
+
   /**
    * Returns DesiredCapabilities for Chrome with these options included as
    * capabilities. This does not copy the options. Further changes will be