Support more configurability in GN toolchains

tools/gn/ninja_build_writer.h

 // Copyright (c) 2013 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_NINJA_BUILD_WRITER_H_
 #define TOOLS_GN_NINJA_BUILD_WRITER_H_
 
 #include <iosfwd>
 #include <vector>
 
-#include "tools/gn/ninja_helper.h"
 #include "tools/gn/path_output.h"
 
 class BuildSettings;
 class Settings;
 class Target;
 
 // Generates the toplevel "build.ninja" file. This references the individual
 // toolchain files and lists all input .gn files as dependencies of the
 // build itself.
 class NinjaBuildWriter {
@@ skipping 20 matching lines @@
   void WritePhonyRule(const Target* target, const OutputFile& target_file,
                       const std::string& phony_name);
 
   const BuildSettings* build_settings_;
   std::vector<const Settings*> all_settings_;
   std::vector<const Target*> default_toolchain_targets_;
   std::ostream& out_;
   std::ostream& dep_out_;
   PathOutput path_output_;
 
-  NinjaHelper helper_;
-
   DISALLOW_COPY_AND_ASSIGN(NinjaBuildWriter);
 };
 
 #endif  // TOOLS_GN_NINJA_BUILD_GENERATOR_H_