Await in websockets

[asvetlov]

Make send_*() and ping()/pong() true coroutines.

Get rid of yield from

[codecov-io]

Codecov Report

Merging #2475 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2475      +/-   ##
==========================================
- Coverage   97.14%   97.14%   -0.01%     
==========================================
  Files          39       39              
  Lines        8127     8125       -2     
  Branches     1419     1419              
==========================================
- Hits         7895     7893       -2     
  Misses        101      101              
  Partials      131      131

Impacted Files	Coverage Δ
aiohttp/payload_streamer.py	100% <ø> (ø)	⬆️
aiohttp/http_writer.py	94.44% <100%> (-0.06%)	⬇️

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[asvetlov]

Need a doc update before merging

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a [new issue] for related bugs.
If you feel like there's important points made in this discussion, please include those exceprts into that [new issue].
[new issue]: https://github.com/aio-libs/aiohttp/issues/new