Implemented event-dispatching for button clicks.

chrome/browser/chromeos/login/screens/eula_model.cc

 // Copyright 2014 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.
 
 #include "chrome/browser/chromeos/login/screens/eula_model.h"
 
 #include "chrome/browser/chromeos/login/wizard_controller.h"
 
 namespace chromeos {
 
+const char EulaModel::kUserActionAcceptButtonClicked[] = "accept-button";
+const char EulaModel::kUserActionBackButtonClicked[] = "back-button";
+const char EulaModel::kContextKeyUsageStatsEnabled[] = "usageStatsEnabled";
+
 EulaModel::EulaModel(BaseScreenDelegate* base_screen_delegate)
     : BaseScreen(base_screen_delegate) {
 }
 
 EulaModel::~EulaModel() {
 }
 
 std::string EulaModel::GetName() const {
   return WizardController::kEulaScreenName;
 }
 
 }  // namespace chromeos