[GN] Add JSON project writer

tools/gn/desc_builder.h

Index: tools/gn/desc_builder.h
diff --git a/tools/gn/desc_builder.h b/tools/gn/desc_builder.h
new file mode 100644
index 0000000000000000000000000000000000000000..bd2aac3cc0fe8fe2a99a9f512b2af8f85399a5fe
--- /dev/null
+++ b/tools/gn/desc_builder.h
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+// 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);
+
+  // Unlike Target::GetStringForOutputType, result of
+  // DescBuilder::GetStringForOutputType matches Target::OutputType enum values
+  static const char* GetStringForOutputType(Target::OutputType type);
+  static Target::OutputType GetOutputTypeForString(const std::string& type);
+};
+
+#endif