[CrOS Tether] Create TetherDisconnector, which disconnects from active tethering sessions.

chromeos/components/tether/disconnect_tethering_operation.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_COMPONENTS_TETHER_DISCONNECT_TETHERING_OPERATION_H_
 #define CHROMEOS_COMPONENTS_TETHER_DISCONNECT_TETHERING_OPERATION_H_
 
 #include "base/observer_list.h"
 #include "chromeos/components/tether/message_transfer_operation.h"
 
@@ skipping 18 matching lines @@
     virtual std::unique_ptr<DisconnectTetheringOperation> BuildInstance(
         const cryptauth::RemoteDevice& device_to_connect,
         BleConnectionManager* connection_manager);
 
    private:
     static Factory* factory_instance_;
   };
 
   class Observer {
    public:
-    // Alerts observers when the operation has finished. |success| is true when
-    // the operation successfully sends the message and false otherwise.
-    virtual void OnOperationFinished(bool success) = 0;
+    // Alerts observers when the operation has finished for device with ID
+    // |device_id|. |success| is true when the operation successfully sends the
+    // message and false otherwise.
+    virtual void OnOperationFinished(const std::string& device_id,
+                                     bool success) = 0;
   };
 
   DisconnectTetheringOperation(const cryptauth::RemoteDevice& device_to_connect,
                                BleConnectionManager* connection_manager);
   ~DisconnectTetheringOperation() override;
 
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
  protected:
+  void NotifyObserversOperationFinished(bool success);
+
   // MessageTransferOperation:
   void OnDeviceAuthenticated(
       const cryptauth::RemoteDevice& remote_device) override;
   void OnOperationFinished() override;
   MessageType GetMessageTypeForConnection() override;
 
  private:
   friend class DisconnectTetheringOperationTest;
 
   base::ObserverList<Observer> observer_list_;
+  std::string device_id_;
   bool has_authenticated_;
 
   DISALLOW_COPY_AND_ASSIGN(DisconnectTetheringOperation);
 };
 
 }  // namespace tether
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_COMPONENTS_TETHER_DISCONNECT_TETHERING_OPERATION_H_