Add GN function get_label_info

tools/gn/loader.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/loader.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "base/stl_util.h"
 #include "tools/gn/build_settings.h"
 #include "tools/gn/err.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/input_file_manager.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scheduler.h"
 #include "tools/gn/scope_per_file_provider.h"
 #include "tools/gn/settings.h"
 #include "tools/gn/source_dir.h"
 #include "tools/gn/source_file.h"
 #include "tools/gn/trace.h"
 
-namespace {
-
-std::string GetOutputSubdirName(const Label& toolchain_label, bool is_default) {
-  // The default toolchain has no subdir.
-  if (is_default)
-    return std::string();
-
-  // For now just assume the toolchain name is always a valid dir name. We may
-  // want to clean up the in the future.
-  return toolchain_label.name();
-}
-
-}  // namespace
-
 // Identifies one time a file is loaded in a given toolchain so we don't load
 // it more than once.
 struct LoaderImpl::LoadID {
   LoadID() {}
   LoadID(const SourceFile& f, const Label& tc_name)
       : file(f),
         toolchain_name(tc_name) {
   }
 
   bool operator<(const LoadID& other) const {
@@ skipping 354 matching lines @@
     const SourceFile& file_name,
     const base::Callback<void(const ParseNode*)>& callback,
     Err* err) {
   if (async_load_file_.is_null()) {
     return g_scheduler->input_file_manager()->AsyncLoadFile(
         origin, build_settings, file_name, callback, err);
   }
   return async_load_file_.Run(
       origin, build_settings, file_name, callback, err);
 }