Implement tracking of BUILD.gn files used to define target, toolchain or

tools/gn/setup.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_SETUP_H_
 #define TOOLS_GN_SETUP_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 67 matching lines @@
   // does not specify anything, this will be null. If the .gn file specifies
   // the empty list, this will be non-null but empty.
   const std::vector<LabelPattern>* check_patterns() const {
     return check_patterns_.get();
   }
 
   BuildSettings& build_settings() { return build_settings_; }
   Builder& builder() { return builder_; }
   LoaderImpl* loader() { return loader_.get(); }
 
+  const InputFile* dotfile_input_file() const {
+    return dotfile_input_file_.get();
+  }
+
   // Name of the file in the root build directory that contains the build
   // arguements.
   static const char kBuildArgFileName[];
 
  private:
   // Performs the two sets of operations to run the generation before and after
   // the message loop is run.
   void RunPreMessageLoop();
   bool RunPostMessageLoop();
 
@@ skipping 64 matching lines @@
   // this around for the entire run so that Values can blame to the command
   // line when we issue errors about them.
   std::unique_ptr<InputFile> args_input_file_;
   std::vector<Token> args_tokens_;
   std::unique_ptr<ParseNode> args_root_;
 
   DISALLOW_COPY_AND_ASSIGN(Setup);
 };
 
 #endif  // TOOLS_GN_SETUP_H_