Consolidate EulaAcceptedNotifier implementations.

chrome/browser/metrics/variations/eula_accepted_notifier.h

 // Copyright (c) 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_METRICS_VARIATIONS_EULA_ACCEPTED_NOTIFIER_H_
 #define CHROME_BROWSER_METRICS_VARIATIONS_EULA_ACCEPTED_NOTIFIER_H_
 
 #include "base/basictypes.h"
+#include "base/prefs/pref_change_registrar.h"
 
-// Interface for querying the EULA accepted state and receiving a notification
-// when the EULA is accepted. This abstracts away the platform-specific logic
-// for EULA notifications on different platforms.
+class PrefService;
+
+// Helper class for querying the EULA accepted state and receiving a
+// notification when the EULA is accepted.
 class EulaAcceptedNotifier {
  public:
   // Observes EULA accepted state changes.
   class Observer {
    public:
     virtual void OnEulaAccepted() = 0;
   };
 
-  EulaAcceptedNotifier();
+  explicit EulaAcceptedNotifier(PrefService* local_state);
   virtual ~EulaAcceptedNotifier();
 
   // Initializes this class with the given |observer|. Must be called before
   // the class is used.
   void Init(Observer* observer);
 
   // Returns true if the EULA has been accepted. If the EULA has not yet been
   // accepted, begins monitoring the EULA state and will notify the observer
   // once the EULA has been accepted.
-  virtual bool IsEulaAccepted() = 0;
+  virtual bool IsEulaAccepted();
 
   // Factory method for this class.
   static EulaAcceptedNotifier* Create();
 
  protected:
-  // Notifies the observer that the EULA has been updated, to be called by
-  // platform-specific subclasses.
+  // Notifies the observer that the EULA has been updated, made protected for
+  // testing.
   void NotifyObserver();
 
  private:
+  // Callback for EULA accepted pref change notification.
+  void OnPrefChanged();
+
+  // Local state pref service for querying the EULA accepted pref.
+  PrefService* local_state_;
+
+  // Used to listen for the EULA accepted pref change notification.
+  PrefChangeRegistrar registrar_;
+
   // Observer of the EULA accepted notification.
   Observer* observer_;
 
   DISALLOW_COPY_AND_ASSIGN(EulaAcceptedNotifier);
 };
 
 #endif  // CHROME_BROWSER_METRICS_VARIATIONS_EULA_ACCEPTED_NOTIFIER_H_