Revert of arc: Implement silent OptIn mode for managed Arc.

chrome/browser/chromeos/arc/arc_auth_context_delegate.h

-// Copyright 2016 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_ARC_ARC_AUTH_CONTEXT_DELEGATE_H_
-#define CHROME_BROWSER_CHROMEOS_ARC_ARC_AUTH_CONTEXT_DELEGATE_H_
-
-namespace arc {
-
-class ArcAuthContextDelegate {
- public:
-  virtual void OnContextReady() = 0;
-  virtual void OnPrepareContextFailed() = 0;
-
- protected:
-  virtual ~ArcAuthContextDelegate() {}
-};
-
-}  // namespace arc
-
-#endif  // CHROME_BROWSER_CHROMEOS_ARC_ARC_AUTH_CONTEXT_DELEGATE_H_