Add PyAuto test for DeviceGuestModeEnabled policy

chrome/browser/automation/automation_provider_observers.h

Index: chrome/browser/automation/automation_provider_observers.h
diff --git a/chrome/browser/automation/automation_provider_observers.h b/chrome/browser/automation/automation_provider_observers.h
index af2e2543bf1473599b3950de643fab915d030afc..bb898146396e625234a6a1b610257af82404d476 100644
--- a/chrome/browser/automation/automation_provider_observers.h
+++ b/chrome/browser/automation/automation_provider_observers.h
@@ -143,11 +143,11 @@ class NetworkManagerInitObserver
   DISALLOW_COPY_AND_ASSIGN(NetworkManagerInitObserver);
 };
 
-// Observes when webui login becomes ready on chromeos.
+// Observes when the WebUI login form or account picker becomes ready on
+// ChromeOS.
 class LoginWebuiReadyObserver : public content::NotificationObserver {
  public:
   explicit LoginWebuiReadyObserver(AutomationProvider* automation);
-  virtual ~LoginWebuiReadyObserver();
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details);