chromium#62.0.3202.75-1 build issue

Traceback (most recent call last): File "../../third_party/dom_distiller_js/protoc_plugins/json_values_converter.py", line 14, in <module> from util import plugin_protos, types, writer File "/home/pkgmk/work/chromium/src/chromium-62.0.3202.75/third_party/dom_distiller_js/protoc_plugins/util/plugin_protos.py", line 22, in <module> from google.protobuf.descriptor_pb2 import FieldDescriptorProto ImportError: No module named protobuf.descriptor_pb2 --plugin_out: protoc-gen-plugin: Plugin failed with status code 1. Protoc has returned non-zero status: 1 . ninja: build stopped: subcommand failed. =======> ERROR: Building '/home/pkgmk/pkg/chromium#62.0.3202.75-1.pkg.tar.xz' failed. Any ideas what's causing this? Thanks.