Add "create_bundle" target in order to support bundle with gn.

tools/gn/gn.gyp

 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
       'target_name': 'gn_lib',
       'type': 'static_library',
       'dependencies': [
         '../../base/base.gyp:base',
       ],
       'sources': [
         'action_target_generator.cc',
         'action_target_generator.h',
         'action_values.cc',
         'action_values.h',
         'args.cc',
         'args.h',
         'binary_target_generator.cc',
         'binary_target_generator.h',
         'build_settings.cc',
         'build_settings.h',
         'builder.cc',
         'builder.h',
         'builder_record.cc',
         'builder_record.h',
+        'bundle_data.cc',
+        'bundle_data.h',
         'bundle_data_target_generator.cc',
         'bundle_data_target_generator.h',
+        'bundle_file_rule.cc',
+        'bundle_file_rule.h',
         'c_include_iterator.cc',
         'c_include_iterator.h',
         'command_args.cc',
         'command_check.cc',
         'command_clean.cc',
         'command_desc.cc',
         'command_format.cc',
         'command_gen.cc',
         'command_help.cc',
         'command_ls.cc',
         'command_path.cc',
         'command_refs.cc',
         'commands.cc',
         'commands.h',
         'config.cc',
         'config.h',
         'config_values.cc',
         'config_values.h',
         'config_values_extractors.cc',
         'config_values_extractors.h',
         'config_values_generator.cc',
         'config_values_generator.h',
         'copy_target_generator.cc',
         'copy_target_generator.h',
+        'create_bundle_target_generator.cc',
+        'create_bundle_target_generator.h',
         'deps_iterator.cc',
         'deps_iterator.h',
         'eclipse_writer.cc',
         'eclipse_writer.h',
         'err.cc',
         'err.h',
         'escape.cc',
         'escape.h',
         'exec_process.cc',
         'exec_process.h',
@@ skipping 46 matching lines @@
         'ninja_action_target_writer.cc',
         'ninja_action_target_writer.h',
         'ninja_binary_target_writer.cc',
         'ninja_binary_target_writer.h',
         'ninja_build_writer.cc',
         'ninja_build_writer.h',
         'ninja_bundle_data_target_writer.cc',
         'ninja_bundle_data_target_writer.h',
         'ninja_copy_target_writer.cc',
         'ninja_copy_target_writer.h',
+        'ninja_create_bundle_target_writer.cc',
+        'ninja_create_bundle_target_writer.h',
         'ninja_group_target_writer.cc',
         'ninja_group_target_writer.h',
         'ninja_target_writer.cc',
         'ninja_target_writer.h',
         'ninja_toolchain_writer.cc',
         'ninja_toolchain_writer.h',
         'ninja_utils.cc',
         'ninja_utils.h',
         'ninja_writer.cc',
         'ninja_writer.h',
@@ skipping 111 matching lines @@
         'functions_unittest.cc',
         'header_checker_unittest.cc',
         'inherited_libraries_unittest.cc',
         'input_conversion_unittest.cc',
         'label_pattern_unittest.cc',
         'label_unittest.cc',
         'loader_unittest.cc',
         'ninja_action_target_writer_unittest.cc',
         'ninja_binary_target_writer_unittest.cc',
         'ninja_copy_target_writer_unittest.cc',
+        'ninja_create_bundle_target_writer_unittest.cc',
         'ninja_group_target_writer_unittest.cc',
         'ninja_target_writer_unittest.cc',
         'ninja_toolchain_writer_unittest.cc',
         'operators_unittest.cc',
         'parse_tree_unittest.cc',
         'parser_unittest.cc',
         'path_output_unittest.cc',
         'pattern_unittest.cc',
         'runtime_deps_unittest.cc',
         'scope_per_file_provider_unittest.cc',
@@ skipping 32 matching lines @@
           'dependencies': [
             'gn_unittests',
           ],
           'includes': [ '../../build/isolate.gypi' ],
           'sources': [ 'gn_unittests.isolate' ],
         },
       ],
     }],
   ],
 }