Support more configurability in GN toolchains

tools/gn/header_checker.cc

 // Copyright 2014 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.
 
 #include "tools/gn/header_checker.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/builder.h"
 #include "tools/gn/c_include_iterator.h"
 #include "tools/gn/config.h"
 #include "tools/gn/err.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/scheduler.h"
+#include "tools/gn/source_file_type.h"
 #include "tools/gn/target.h"
 #include "tools/gn/trace.h"
 
 namespace {
 
 // This class makes InputFiles on the stack as it reads files to check. When
 // we throw an error, the Err indicates a locatin which has a pointer to
 // an InputFile that must persist as long as the Err does.
 //
 // To make this work, this function creates a clone of the InputFile managed
@@ skipping 453 matching lines @@
         chain[i]->forward_dependent_configs();
     if (std::find_if(forwarded.begin(), forwarded.end(),
                      LabelPtrPtrEquals<Target>(chain[i - 1])) ==
         forwarded.end())
       return i;
   }
 
   CHECK(false) << "Unable to diagnose dependent config chain problem.";
   return 0;
 }