Delete some dead code.

tools/gn/command_desc.cc

 // 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.
 
 #include <algorithm>
 #include <set>
 #include <sstream>
 
 #include "base/command_line.h"
 #include "tools/gn/commands.h"
@@ skipping 168 matching lines @@
       << location.line_number() << ")\n";
 }
 
 // Templatized writer for writing out different config value types.
 template<typename T> struct DescValueWriter {};
 template<> struct DescValueWriter<std::string> {
   void operator()(const std::string& str, std::ostream& out) const {
     out << "    " << str << "\n";
   }
 };
-template<> struct DescValueWriter<SourceFile> {
-  void operator()(const SourceFile& file, std::ostream& out) const {
-    out << "    " << file.value() << "\n";
-  }
-};
 template<> struct DescValueWriter<SourceDir> {
   void operator()(const SourceDir& dir, std::ostream& out) const {
     out << "    " << FormatSourceDir(dir) << "\n";
   }
 };
 
 // Writes a given config value type to the string, optionally with attribution.
 // This should match RecursiveTargetConfigToStream in the order it traverses.
 template<typename T> void OutputRecursiveTargetConfig(
     const Target* target,
@@ skipping 176 matching lines @@
   OUTPUT_CONFIG_VALUE(ldflags, std::string)
   PrintLibs(target, true);
   PrintLibDirs(target, true);
 
   PrintDeps(target, true);
 
   return 0;
 }
 
 }  // namespace commands