UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/51.0.2704.63 Safari/537.36

Steps to reproduce the problem:
1. Build chromium for android

What is the expected behavior?

What went wrong?
[3/11853] ACTION //chrome/browser/resources/safe_browsing:make_file_types_protobuf(//build/toolchain/android:clang_arm)
FAILED: gen/chrome/browser/resources/safe_browsing/download_file_types.pb 
python ../../chrome/browser/resources/safe_browsing/gen_file_type_proto.py -w -t android -i ../../chrome/browser/resources/safe_browsing/download_file_types.asciipb -d gen/chrome/browser/resources/safe_browsing -o download_file_types.pb -p pyproto -p pyproto/chrome/common/safe_browsing
Traceback (most recent call last):
  File "../../chrome/browser/resources/safe_browsing/gen_file_type_proto.py", line 13, in <module>
    import optparse
ImportError: No module named optparse

Did this work before? N/A 

Chrome version: 51.0.2704.63  Channel: stable
OS Version: 
Flash Version: