Make the SigninErrorController a PKS.

components/signin/core/browser/signin_error_controller.h

 // 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.
 
 #ifndef COMPONENTS_SIGNIN_CORE_BROWSER_SIGNIN_ERROR_CONTROLLER_H_
 #define COMPONENTS_SIGNIN_CORE_BROWSER_SIGNIN_ERROR_CONTROLLER_H_
 
 #include <set>
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/observer_list.h"
+#include "components/keyed_service/core/keyed_service.h"
 #include "google_apis/gaia/google_service_auth_error.h"
 
 // Keep track of auth errors and expose them to observers in the UI. Services
 // that wish to expose auth errors to the user should register an
 // AuthStatusProvider to report their current authentication state, and should
 // invoke AuthStatusChanged() when their authentication state may have changed.
-class SigninErrorController {
+class SigninErrorController : public KeyedService {
  public:
   class AuthStatusProvider {
    public:
     AuthStatusProvider();
     virtual ~AuthStatusProvider();
 
     // Returns the account id with the status specified by GetAuthStatus().
     virtual std::string GetAccountId() const = 0;
 
     // Returns the username with the status specified by GetAuthStatus().
     virtual std::string GetUsername() const = 0;
 
     // API invoked by SigninErrorController to get the current auth status of
     // the various signed in services.
     virtual GoogleServiceAuthError GetAuthStatus() const = 0;
   };
 
   // The observer class for SigninErrorController lets the controller notify
   // observers when an error arises or changes.
   class Observer {
    public:
     virtual ~Observer() {}
     virtual void OnErrorChanged() = 0;
   };
 
   SigninErrorController();
-  ~SigninErrorController();
+  ~SigninErrorController() override;
 
   // Adds a provider which the SigninErrorController object will start querying
   // for auth status.
   void AddProvider(const AuthStatusProvider* provider);
 
   // Removes a provider previously added by SigninErrorController (generally
   // only called in preparation for shutdown).
   void RemoveProvider(const AuthStatusProvider* provider);
 
   // Invoked when the auth status of an AuthStatusProvider has changed.
@@ skipping 19 matching lines @@
   // The auth error detected the last time AuthStatusChanged() was invoked (or
   // NONE if AuthStatusChanged() has never been invoked).
   GoogleServiceAuthError auth_error_;
 
   ObserverList<Observer, false> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(SigninErrorController);
 };
 
 #endif  // COMPONENTS_SIGNIN_CORE_BROWSER_SIGNIN_ERROR_CONTROLLER_H_