GN: Use build directory for CD for scripts

tools/gn/gn.gyp

 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
       'target_name': 'gn_lib',
       'type': 'static_library',
       'dependencies': [
         '../../base/base.gyp:base',
@@ skipping 33 matching lines @@
         'filesystem_utils.h',
         'functions_target.cc',
         'functions.cc',
         'functions.h',
         'function_exec_script.cc',
         'function_process_file_template.cc',
         'function_read_file.cc',
         'function_set_default_toolchain.cc',
         'function_set_defaults.cc',
         'function_template.cc',
+        'function_to_build_path.cc',
         'function_toolchain.cc',
         'function_write_file.cc',
         'group_target_generator.cc',
         'group_target_generator.h',
         'import_manager.cc',
         'import_manager.h',
         'input_conversion.cc',
         'input_conversion.h',
         'input_file.cc',
         'input_file.h',
@@ skipping 94 matching lines @@
         '../../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
       ],
     },
     {
       'target_name': 'gn_unittests',
       'type': '<(gtest_target_type)',
       'sources': [
         'escape_unittest.cc',
         'file_template_unittest.cc',
         'filesystem_utils_unittest.cc',
+        'function_to_build_path_unittest.cc',
         'input_conversion_unittest.cc',
         'label_unittest.cc',
         'ninja_helper_unittest.cc',
         'parser_unittest.cc',
         'path_output_unittest.cc',
         'pattern_unittest.cc',
         'scope_per_file_provider_unittest.cc',
         'source_dir_unittest.cc',
         'string_utils_unittest.cc',
         'target_generator_unittest.cc',
         'target_manager_unittest.cc',
         'target_unittest.cc',
+        'test_with_scope.cc',
+        'test_with_scope.h',
         'tokenizer_unittest.cc',
       ],
       'dependencies': [
         'gn_lib',
         '../../base/base.gyp:run_all_unittests',
         '../../base/base.gyp:test_support_base',
         '../../testing/gtest.gyp:gtest',
       ],
     },
     {
       'target_name': 'generate_test_gn_data',
       'type': 'executable',
       'sources': [
         'generate_test_gn_data.cc',
       ],
       'dependencies': [
         '../../base/base.gyp:base',
       ],
     }
   ],
 }