Fix BundleData::GetBundleRootDirOutput() for non-default toolchain.

tools/gn/ninja_group_target_writer_unittest.cc

 // Copyright 2014 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/ninja_group_target_writer.h"
 #include "tools/gn/target.h"
 #include "tools/gn/test_with_scope.h"
 
 TEST(NinjaGroupTargetWriter, Run) {
+  Err err;
   TestWithScope setup;
-  Err err;
 
-  setup.build_settings()->SetBuildDir(SourceDir("//out/Debug/"));
   Target target(setup.settings(), Label(SourceDir("//foo/"), "bar"));
-
   target.set_output_type(Target::GROUP);
   target.visibility().SetPublic();
 
   Target dep(setup.settings(), Label(SourceDir("//foo/"), "dep"));
   dep.set_output_type(Target::ACTION);
   dep.visibility().SetPublic();
   dep.SetToolchain(setup.toolchain());
   ASSERT_TRUE(dep.OnResolved(&err));
 
   Target dep2(setup.settings(), Label(SourceDir("//foo/"), "dep2"));
@@ skipping 16 matching lines @@
   ASSERT_TRUE(target.OnResolved(&err));
 
   std::ostringstream out;
   NinjaGroupTargetWriter writer(&target, out);
   writer.Run();
 
   const char expected[] =
       "build obj/foo/bar.stamp: stamp obj/foo/dep.stamp obj/foo/dep2.stamp || obj/foo/datadep.stamp\n";
   EXPECT_EQ(expected, out.str());
 }