Remove all blimp engine code

blimp/engine/common/blimp_content_client.h

-// Copyright (c) 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_ENGINE_COMMON_BLIMP_CONTENT_CLIENT_H_
-#define BLIMP_ENGINE_COMMON_BLIMP_CONTENT_CLIENT_H_
-
-#include <string>
-
-#include "content/public/common/content_client.h"
-
-namespace blimp {
-namespace engine {
-
-std::string GetBlimpEngineUserAgent();
-void SetClientOSInfo(std::string client_os_info);
-
-class BlimpContentClient : public content::ContentClient {
- public:
-  ~BlimpContentClient() override;
-
-  // content::ContentClient implementation.
-  std::string GetUserAgent() const override;
-  base::string16 GetLocalizedString(int message_id) const override;
-  base::StringPiece GetDataResource(
-      int resource_id,
-      ui::ScaleFactor scale_factor) const override;
-  base::RefCountedMemory* GetDataResourceBytes(
-      int resource_id) const override;
-  gfx::Image& GetNativeImageNamed(int resource_id) const override;
-};
-
-}  // namespace engine
-}  // namespace blimp
-
-#endif  // BLIMP_ENGINE_COMMON_BLIMP_CONTENT_CLIENT_H_