Revert of [CrOS Tether] Add the notion of a tether DeviceState.

chromeos/components/tether/tether_device_state_manager.cc

-// 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.
-
-#include "chromeos/components/tether/tether_device_state_manager.h"
-
-#include "chromeos/network/network_state_handler.h"
-
-namespace chromeos {
-
-namespace tether {
-
-TetherDeviceStateManager::TetherDeviceStateManager(
-    NetworkStateHandler* network_state_handler)
-    : network_state_handler_(network_state_handler) {
-  network_state_handler_->AddObserver(this, FROM_HERE);
-
-  // TODO(hansberry): Set the appropriate value. For now, always set ENABLED.
-  network_state_handler_->SetTetherTechnologyState(
-      NetworkStateHandler::TechnologyState::TECHNOLOGY_ENABLED);
-}
-
-TetherDeviceStateManager::~TetherDeviceStateManager() {
-  network_state_handler_->RemoveObserver(this, FROM_HERE);
-
-  // TODO(hansberry): Determine if this should be PROHIBITED or UNAVAILABLE
-  // based on reason for shutting down.
-  network_state_handler_->SetTetherTechnologyState(
-      NetworkStateHandler::TechnologyState::TECHNOLOGY_UNAVAILABLE);
-}
-
-void TetherDeviceStateManager::DeviceListChanged() {
-  // TODO(hansberry): Implement.
-}
-
-}  // namespace tether
-
-}  // namespace chromeos