Revert of [GN] Add JSON project writer

tools/gn/desc_builder.h

-// Copyright (c) 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 TOOLS_GN_DESC_BUILDER_H_
-#define TOOLS_GN_DESC_BUILDER_H_
-
-#include "base/values.h"
-#include "tools/gn/target.h"
-
-class DescBuilder {
- public:
-  // Creates Dictionary representation for given target
-  static std::unique_ptr<base::DictionaryValue> DescriptionForTarget(
-      const Target* target,
-      const std::string& what,
-      bool all,
-      bool tree,
-      bool blame);
-
-  // Creates Dictionary representation for given config
-  static std::unique_ptr<base::DictionaryValue> DescriptionForConfig(
-      const Config* config,
-      const std::string& what);
-};
-
-#endif