Remove SigninDelegateObserver.

ui/app_list/signin_delegate_observer.h

Index: ui/app_list/signin_delegate_observer.h
diff --git a/ui/app_list/signin_delegate_observer.h b/ui/app_list/signin_delegate_observer.h
deleted file mode 100644
index 47c499260ef7b0e9cd03f7c404495dab0a4d0753..0000000000000000000000000000000000000000
--- a/ui/app_list/signin_delegate_observer.h
+++ /dev/null
@@ -1,24 +0,0 @@
-// 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 UI_APP_LIST_SIGNIN_DELEGATE_OBSERVER_H_
-#define UI_APP_LIST_SIGNIN_DELEGATE_OBSERVER_H_
-
-#include "ui/app_list/app_list_export.h"
-
-namespace app_list {
-
-// Abstract interface to allow handling app list signin success.
-class APP_LIST_EXPORT SigninDelegateObserver {
- public:
-  // Called by the SigninDelegate when signin has successfully completed.
-  virtual void OnSigninSuccess() = 0;
-
- protected:
-  virtual ~SigninDelegateObserver() {}
-};
-
-}  // namespace app_list
-
-#endif  // UI_APP_LIST_SIGNIN_DELEGATE_OBSERVER_H_