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

tools/gn/ninja_bundle_data_target_writer_unittest.cc

 // Copyright 2016 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/ninja_bundle_data_target_writer.h"
 
 #include <algorithm>
 #include <sstream>
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "tools/gn/target.h"
 #include "tools/gn/test_with_scope.h"
 
 TEST(NinjaBundleDataTargetWriter, Run) {
   Err err;
-
   TestWithScope setup;
-  setup.build_settings()->SetBuildDir(SourceDir("//out/Debug/"));
 
   Target bundle_data(setup.settings(), Label(SourceDir("//foo/"), "data"));
   bundle_data.set_output_type(Target::BUNDLE_DATA);
   bundle_data.sources().push_back(SourceFile("//foo/input1.txt"));
   bundle_data.sources().push_back(SourceFile("//foo/input2.txt"));
   bundle_data.sources().push_back(
       SourceFile("//foo/Foo.xcassets/Contents.json"));
   bundle_data.sources().push_back(
       SourceFile("//foo/Foo.xcassets/foo.imageset/Contents.json"));
   bundle_data.sources().push_back(
@@ skipping 17 matching lines @@
           "../../foo/input1.txt "
           "../../foo/input2.txt "
           "../../foo/Foo.xcassets/Contents.json "
           "../../foo/Foo.xcassets/foo.imageset/Contents.json "
           "../../foo/Foo.xcassets/foo.imageset/FooIcon-29.png "
           "../../foo/Foo.xcassets/foo.imageset/FooIcon-29@2x.png "
           "../../foo/Foo.xcassets/foo.imageset/FooIcon-29@3x.png\n";
   std::string out_str = out.str();
   EXPECT_EQ(expected, out_str);
 }