[CrOS Tether] Add HasConnectedToHost property for Tether networks.

chromeos/network/tether_constants.h

 // Copyright 2017 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 CHROMEOS_NETWORK_TETHER_CONSTANTS_H_
 #define CHROMEOS_NETWORK_TETHER_CONSTANTS_H_
 
 #include "chromeos/chromeos_export.h"
 
 namespace chromeos {
 
 // This file contains constants for Chrome OS tether networks which are used
 // wherever Shill constants are appropriate. Tether networks are a Chrome OS
 // concept which does not exist as part of Shill, so these custom definitions
 // are used instead. Tether networks are never intended to be passed to Shill
 // code, so these constants are used primarily as part of NetworkStateHandler.
 
 // Represents the tether network type.
 CHROMEOS_EXPORT extern const char kTypeTether[];
 
 // Properties associated with tether networks.
 CHROMEOS_EXPORT extern const char kTetherBatteryPercentage[];
 CHROMEOS_EXPORT extern const char kTetherCarrier[];
+CHROMEOS_EXPORT extern const char kTetherHasConnectedToHost[];
 CHROMEOS_EXPORT extern const char kTetherSignalStrength[];
 
 // The device path used for the tether DeviceState.
 CHROMEOS_EXPORT extern const char kTetherDevicePath[];
 
 // The name used for the tether DeviceState.
 CHROMEOS_EXPORT extern const char kTetherDeviceName[];
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_NETWORK_TETHER_CONSTANTS_H_