gn: Do not advertise a rebase_path() command with more than 3 parameters.

tools/gn/function_rebase_path.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 "tools/gn/build_settings.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
 #include "tools/gn/settings.h"
@@ skipping 167 matching lines @@
     "  # Convert a file in the current directory to be relative to the build\n"
     "  # directory (the current dir when executing compilers and scripts).\n"
     "  foo = rebase_path(\"myfile.txt\", root_build_dir)\n"
     "  # might produce \"../../project/myfile.txt\".\n"
     "\n"
     "  # Convert a file to be system absolute:\n"
     "  foo = rebase_path(\"myfile.txt\")\n"
     "  # Might produce \"D:\\source\\project\\myfile.txt\" on Windows or\n"
     "  # \"/home/you/source/project/myfile.txt\" on Linux.\n"
     "\n"
-    "  # Convert a file's path separators from forward slashes to system\n"
-    "  # slashes.\n"
-    "  foo = rebase_path(\"source/myfile.txt\", \".\", \".\", \"to_system\")\n"
-    "\n"
     "  # Typical usage for converting to the build directory for a script.\n"
     "  action(\"myscript\") {\n"
     "    # Don't convert sources, GN will automatically convert these to be\n"
     "    # relative to the build directory when it contructs the command\n"
     "    # line for your script.\n"
     "    sources = [ \"foo.txt\", \"bar.txt\" ]\n"
     "\n"
     "    # Extra file args passed manually need to be explicitly converted\n"
     "    # to be relative to the build directory:\n"
     "    args = [\n"
@@ skipping 70 matching lines @@
     }
     return result;
   }
 
   *err = Err(function->function(),
              "rebase_path requires a list or a string.");
   return result;
 }
 
 }  // namespace functions