GN: toolchain threading cleanup

tools/gn/ninja_helper_unittest.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 "testing/gtest/include/gtest/gtest.h"
 
 #include "tools/gn/build_settings.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/ninja_helper.h"
 #include "tools/gn/settings.h"
 #include "tools/gn/target.h"
 #include "tools/gn/toolchain.h"
 
 namespace {
 
 class HelperSetterUpper {
  public:
   HelperSetterUpper()
       : build_settings(),
-        toolchain(Label(SourceDir("//"), "tc")),
-        settings(&build_settings, &toolchain, std::string()),
+        settings(&build_settings, std::string()),
+        toolchain(&settings, Label(SourceDir("//"), "tc")),
         target(&settings, Label(SourceDir("//tools/gn/"), "name")) {
+    settings.set_toolchain_label(toolchain.label());
     settings.set_target_os(Settings::WIN);
 
     // Output going to "out/Debug".
     build_settings.SetBuildDir(SourceDir("/out/Debug/"));
 
     // Our source target is in "tools/gn".
     target.set_output_type(Target::EXECUTABLE);
   }
 
   BuildSettings build_settings;
@@ skipping 30 matching lines @@
   EXPECT_EQ(OutputFile("name.exe"),
             helper.GetTargetOutputFile(&setup.target));
 
   // Static library on Windows goes alongside the object files.
   setup.target.set_output_type(Target::STATIC_LIBRARY);
   EXPECT_EQ(OutputFile("obj/tools/gn/name.lib"),
             helper.GetTargetOutputFile(&setup.target));
 
   // TODO(brettw) test output to library and other OS types.
 }