gn: Use the term 'out_dir' consistently when referring to the output directory.

tools/gn/command_gen.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 "base/atomicops.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/timer/elapsed_timer.h"
 #include "tools/gn/build_settings.h"
@@ skipping 33 matching lines @@
 }
 
 }  // namespace
 
 const char kGen[] = "gen";
 const char kGen_HelpShort[] =
     "gen: Generate ninja files.";
 const char kGen_Help[] =
     "gn gen: Generate ninja files.\n"
     "\n"
-    "  gn gen <output_directory>\n"
+    "  gn gen <out_dir>\n"
     "\n"
     "  Generates ninja files from the current tree and puts them in the given\n"
     "  output directory.\n"
     "\n"
     "  The output directory can be a source-repo-absolute path name such as:\n"
     "      //out/foo\n"
     "  Or it can be a directory relative to the current directory such as:\n"
     "      out/foo\n"
     "\n"
     "  See \"gn help\" for the common command-line switches.\n";
@@ skipping 48 matching lines @@
             setup->scheduler().input_file_manager()->GetInputFileCount()) +
         " files in " +
         base::Int64ToString(elapsed_time.InMilliseconds()) + "ms\n";
     OutputString(stats);
   }
 
   return 0;
 }
 
 }  // namespace commands