Remove all blimp client code.

blimp/client/core/session/network_event_observer.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 BLIMP_CLIENT_CORE_SESSION_NETWORK_EVENT_OBSERVER_H_
-#define BLIMP_CLIENT_CORE_SESSION_NETWORK_EVENT_OBSERVER_H_
-
-namespace blimp {
-namespace client {
-
-// A NetworkEventObserver is informed whenever changes happen to the connection
-// to the Blimp engine.
-class NetworkEventObserver {
- public:
-  NetworkEventObserver() {}
-  virtual ~NetworkEventObserver() {}
-
-  virtual void OnConnected() = 0;
-  virtual void OnDisconnected(int result) = 0;
-};
-
-}  // namespace client
-}  // namespace blimp
-
-#endif  // BLIMP_CLIENT_CORE_SESSION_NETWORK_EVENT_OBSERVER_H_