Remove all blimp engine code

blimp/engine/app/blimp_system_url_request_context_getter.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_ENGINE_APP_BLIMP_SYSTEM_URL_REQUEST_CONTEXT_GETTER_H_
-#define BLIMP_ENGINE_APP_BLIMP_SYSTEM_URL_REQUEST_CONTEXT_GETTER_H_
-
-#include "base/files/file_path.h"
-#include "base/macros.h"
-#include "content/public/browser/content_browser_client.h"
-#include "net/url_request/url_request_context_getter.h"
-
-namespace base {
-class SingleThreadTaskRunner;
-}
-
-namespace blimp {
-namespace engine {
-
-// The URLRequestContextGetter for Blimp system requests that should not be
-// associated with a user URL request context (e.g. metrics upload).
-class BlimpSystemURLRequestContextGetter : public net::URLRequestContextGetter {
- public:
-  BlimpSystemURLRequestContextGetter();
-
-  // net::URLRequestContextGetter implementation.
-  net::URLRequestContext* GetURLRequestContext() override;
-  scoped_refptr<base::SingleThreadTaskRunner> GetNetworkTaskRunner()
-      const override;
-
- private:
-  ~BlimpSystemURLRequestContextGetter() override;
-
-  std::unique_ptr<net::URLRequestContext> url_request_context_;
-
-  DISALLOW_COPY_AND_ASSIGN(BlimpSystemURLRequestContextGetter);
-};
-
-}  // namespace engine
-}  // namespace blimp
-
-#endif  // BLIMP_ENGINE_APP_BLIMP_SYSTEM_URL_REQUEST_CONTEXT_GETTER_H_