Revert "chromeos: Move files in //ash/common to //ash, part 1"

ash/system/network/network_portal_detector_observer.h

Index: ash/system/network/network_portal_detector_observer.h
diff --git a/ash/system/network/network_portal_detector_observer.h b/ash/system/network/network_portal_detector_observer.h
deleted file mode 100644
index aa2b3949e903f33c0ef1ef8b93166b407e77b0ee..0000000000000000000000000000000000000000
--- a/ash/system/network/network_portal_detector_observer.h
+++ /dev/null
@@ -1,23 +0,0 @@
-// 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 ASH_SYSTEM_NETWORK_NETWORK_PORTAL_DETECTOR_OBSERVER_H_
-#define ASH_SYSTEM_NETWORK_NETWORK_PORTAL_DETECTOR_OBSERVER_H_
-
-#include <string>
-
-namespace ash {
-
-class NetworkPortalDetectorObserver {
- public:
-  virtual ~NetworkPortalDetectorObserver() {}
-
-  // Called when captive portal is detected for the network associated with
-  // |guid|.
-  virtual void OnCaptivePortalDetected(const std::string& guid) = 0;
-};
-
-}  // namespace ash
-
-#endif  // ASH_SYSTEM_NETWORK_NETWORK_PORTAL_DETECTOR_OBSERVER_H_