Added UMA metrics for ChromeOS first-run UI.

chrome/browser/chromeos/first_run/steps/tray_step.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_CHROMEOS_FIRST_RUN_STEPS_TRAY_STEP_H_
 #define CHROME_BROWSER_CHROMEOS_FIRST_RUN_STEPS_TRAY_STEP_H_
 
 #include "base/compiler_specific.h"
 #include "chrome/browser/chromeos/first_run/step.h"
 
 namespace chromeos {
 namespace first_run {
 
 class TrayStep : public Step {
  public:
   TrayStep(ash::FirstRunHelper* shell_helper, FirstRunActor* actor);
 
+ private:
   // Overriden from Step.
-  virtual void Show() OVERRIDE;
+  virtual void DoShow() OVERRIDE;
+
+  DISALLOW_COPY_AND_ASSIGN(TrayStep);
 };
 
 }  // namespace first_run
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FIRST_RUN_STEPS_TRAY_STEP_H_