Support more configurability in GN toolchains

tools/gn/path_output.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_PATH_OUTPUT_H_
 #define TOOLS_GN_PATH_OUTPUT_H_
 
 #include <iosfwd>
 #include <string>
 
@@ skipping 32 matching lines @@
 
   // Getter/setters for flags inside the escape options.
   bool inhibit_quoting() const { return options_.inhibit_quoting; }
   void set_inhibit_quoting(bool iq) { options_.inhibit_quoting = iq; }
   void set_escape_platform(EscapingPlatform p) { options_.platform = p; }
 
   void WriteFile(std::ostream& out, const SourceFile& file) const;
   void WriteFile(std::ostream& out, const OutputFile& file) const;
   void WriteFile(std::ostream& out, const base::FilePath& file) const;
 
+  // Writes the given OutputFiles with spaces separating them. This will also
+  // write an initial space before the first item.
+  void WriteFiles(std::ostream& out,
+                  const std::vector<OutputFile>& files) const;
+
   // This variant assumes the dir ends in a trailing slash or is empty.
   void WriteDir(std::ostream& out,
                 const SourceDir& dir,
                 DirSlashEnding slash_ending) const;
 
   void WriteDir(std::ostream& out,
                 const OutputFile& file,
                 DirSlashEnding slash_ending) const;
 
   // Backend for WriteFile and WriteDir. This appends the given file or
@@ skipping 10 matching lines @@
 
   // Uses system slashes if convert_slashes_to_system_.
   std::string inverse_current_dir_;
 
   // Since the inverse_current_dir_ depends on some of these, we don't expose
   // this directly to modification.
   EscapeOptions options_;
 };
 
 #endif  // TOOLS_GN_PATH_OUTPUT_H_