Added UI to enable debugging features on CrOS

chrome/browser/chromeos/login/existing_user_controller.h

Index: chrome/browser/chromeos/login/existing_user_controller.h
diff --git a/chrome/browser/chromeos/login/existing_user_controller.h b/chrome/browser/chromeos/login/existing_user_controller.h
index 1ea059afae5f5106eba4dc9fe3939ef006721ded..baab97824185c295d2705a39c04997afa176d790 100644
--- a/chrome/browser/chromeos/login/existing_user_controller.h
+++ b/chrome/browser/chromeos/login/existing_user_controller.h
@@ -90,6 +90,7 @@ class ExistingUserController : public LoginDisplay::Delegate,
   virtual void MigrateUserData(const std::string& old_password) override;
   virtual void OnSigninScreenReady() override;
   virtual void OnStartEnterpriseEnrollment() override;
+  virtual void OnStartEnableDebuggingScreen() override;
   virtual void OnStartKioskEnableScreen() override;
   virtual void OnStartKioskAutolaunchScreen() override;
   virtual void ResetPublicSessionAutoLoginTimer() override;
@@ -192,6 +193,9 @@ class ExistingUserController : public LoginDisplay::Delegate,
   // Shows "reset device" screen.
   void ShowResetScreen();
 
+  // Shows "enable developer features" screen.
+  void ShowEnableDebuggingScreen();
+
   // Shows kiosk feature enable screen.
   void ShowKioskEnableScreen();