Remove all blimp network code.

blimp/net/connection_handler.h

-// Copyright 2015 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_NET_CONNECTION_HANDLER_H_
-#define BLIMP_NET_CONNECTION_HANDLER_H_
-
-#include <memory>
-
-namespace blimp {
-
-class BlimpConnection;
-
-// Interface for objects that can take possession of BlimpConnections.
-class ConnectionHandler {
- public:
-  virtual ~ConnectionHandler() {}
-
-  virtual void HandleConnection(
-      std::unique_ptr<BlimpConnection> connection) = 0;
-};
-
-}  // namespace blimp
-
-#endif  // BLIMP_NET_CONNECTION_HANDLER_H_