Improve GN handling of directory templates.

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"
 
 // 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.
   std::vector<std::string>& args() { return args_; }
   const std::vector<std::string>& args() const { return args_; }
-  void swap_in_args(std::vector<std::string>* a) { args_.swap(*a); }
 
-  // Files created by the script.
-  std::vector<SourceFile>& outputs() { return outputs_; }
-  const std::vector<SourceFile>& outputs() const { return outputs_; }
-  void swap_in_outputs(std::vector<SourceFile>* op) { outputs_.swap(*op); }
+  // Files created by the script. These are strings rather than SourceFiles
+  // since they will often contain {{source expansions}}.
+  std::vector<std::string>& outputs() { return outputs_; }
+  const std::vector<std::string>& outputs() const { return outputs_; }
 
   // Depfile generated by the script.
   const SourceFile& depfile() const { return depfile_; }
   bool has_depfile() const { return !depfile_.is_null(); }
   void set_depfile(const SourceFile& depfile) { depfile_ = depfile; }
 
  private:
   SourceFile script_;
   std::vector<std::string> args_;
-  std::vector<SourceFile> outputs_;
+  std::vector<std::string> outputs_;
   SourceFile depfile_;
 
   DISALLOW_COPY_AND_ASSIGN(ActionValues);
 };
 
 #endif  // TOOLS_GN_ACTION_VALUES_H_