Use protobuf utilities instead.
packager/base/json_writer comes from Chromium base. We are going
to switch to abseil which does not have a JSON library.
This is unfortunately, at the expense of increased output binary size.
packager binary increases by about 300KB due to:
- Protos cannot be compiled with LITE_RUNTIME any more.
- Additional protobuf library needed to convert between JSON and proto.
Change-Id: I45a497376925b42d147ffcaabcfc2fa4dbdeacc1
b209aeeb7a