Add outputs to GN's header checker.

tools/gn/action_values.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_ACTION_VALUES_H_
 #define TOOLS_GN_ACTION_VALUES_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "tools/gn/source_file.h"
 #include "tools/gn/substitution_list.h"
 
+class Target;
+
 // Holds the values (outputs, args, script name, etc.) for either an action or
 // an action_foreach target.
 class ActionValues {
  public:
   ActionValues();
   ~ActionValues();
 
   // Filename of the script to execute.
   const SourceFile& script() const { return script_; }
   void set_script(const SourceFile& s) { script_ = s; }
 
   // Arguments to the script.
   SubstitutionList& args() { return args_; }
   const SubstitutionList& args() const { return args_; }
 
   // Files created by the script. These are strings rather than SourceFiles
   // since they will often contain {{source expansions}}.
   SubstitutionList& outputs() { return outputs_; }
   const SubstitutionList& outputs() const { return outputs_; }
 
+  // Expands the outputs() above to the final SourceFile list.
+  void GetOutputsAsSourceFiles(const Target* target,
+                               std::vector<SourceFile>* result) const;
+
   // Depfile generated by the script.
   const SubstitutionPattern& depfile() const { return depfile_; }
   bool has_depfile() const { return !depfile_.ranges().empty(); }
   void set_depfile(const SubstitutionPattern& depfile) { depfile_ = depfile; }
 
  private:
   SourceFile script_;
   SubstitutionList args_;
   SubstitutionList outputs_;
   SubstitutionPattern depfile_;
 
   DISALLOW_COPY_AND_ASSIGN(ActionValues);
 };
 
 #endif  // TOOLS_GN_ACTION_VALUES_H_