rdsmith@: how should we go about adding more logging in the upload code to tell what is blocking the upload? What events will be useful?

If someone who is familiar with the upload code can outline a possible approach, it will make this bug much more likely to be fixed. 

Maybe make UploadDataStream::Init take in a BoundNetLog, and then have it emit events to the log as reads/writes start and complete?

Just in case you're waiting for a comment from me: I don't know the upload code at all, so either Matt's suggestion or reading the code and figuring it out?  Sorry :-{.

I'm probably the only one on the team that's familiar with the upload code.  Happy to talk to anyone about specifics here.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/819ba85927138d71e488fb7a006d10e7abeec01b

commit 819ba85927138d71e488fb7a006d10e7abeec01b
Author: maksim.sisov <maksim.sisov@intel.com>
Date: Wed Aug 17 08:22:52 2016

Add net log to UploadDataStream.

Improve the granularity of net-internals logging for upload
to be able to discover where the hang is occurring in
situations like in the  issue 611436 .

BUG= 613337 

Review-Url: https://codereview.chromium.org/2227503003
Cr-Commit-Position: refs/heads/master@{#412474}

[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/chrome/browser/devtools/devtools_network_controller_unittest.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/chrome/browser/devtools/devtools_network_upload_data_stream.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/chrome/browser/devtools/devtools_network_upload_data_stream.h
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/components/cronet/android/cronet_upload_data_stream.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/components/cronet/android/cronet_upload_data_stream.h
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/components/cronet/android/test/test_upload_data_stream_handler.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/components/domain_reliability/uploader_unittest.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/content/browser/loader/resource_loader_unittest.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/content/browser/loader/upload_data_stream_builder_unittest.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/base/chunked_upload_data_stream.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/base/chunked_upload_data_stream.h
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/base/chunked_upload_data_stream_unittest.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/base/elements_upload_data_stream.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/base/elements_upload_data_stream.h
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/base/elements_upload_data_stream_unittest.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/base/upload_data_stream.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/base/upload_data_stream.h
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/http/http_network_transaction.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/http/http_stream_parser_unittest.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/log/net_log_event_type_list.h
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/quic/chromium/quic_http_stream_test.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/quic/core/quic_end_to_end_unittest.cc
[modify] https://crrev.com/819ba85927138d71e488fb7a006d10e7abeec01b/net/spdy/spdy_http_stream_unittest.cc