Landing Recent QUIC Changes.

Landing Recent QUIC Changes.

Ensure the QuicConnection's writer is not write blocked before trying to
write another packet.

Fix for Chrome crash bug 409191.

Merge internal change: 74635422

BUG=409191

Nest a QUIC SerializedPacket inside a QUIC QueuedPacket.

Merge internal change: 74239145
https://codereview.chromium.org/509203003/

Remove PacketType from QUIC because the QUEUED type is not used and the
other types can be reduced to a bool.

Merge internal change: 74148481
https://codereview.chromium.org/515003003/

Don't send a QUIC SCUP message until after handshake confirmed.

A server config update was occasionally being sent before the crypto
handshake was complete, causing the client to close the connection.

Merge internal change: 74132773
https://codereview.chromium.org/516713002/

Change TransmissionInfo's all_transmissions SequenceNumberSet* to
default to NULL, and only be present if there are multiple transmissions.

Estimated to save ~2% of CPU.

Merge internal change: 74076012
https://codereview.chromium.org/509073004/

Log the quic version for internal server tracing.
Not used in production.

Merge internal change: 74069715
https://codereview.chromium.org/514043002/

Optimize QuicUnackedPacketMap by changing from a LinkedHashMap to a
deque.

Estimated to save ~3% of CPU based on pprof profiling of 100 large gets
on tools/quic/end_to_end_test.cc.

Merge internal change: 74054196
https://codereview.chromium.org/514033002/

Unit test for empty packet closes QUIC connection bug.

Merge internal change: 74041239
https://codereview.chromium.org/495423011/

Log the QUIC transmission type in QUIC internal server trace visitor.
Not used in production.

Merge internal change: 73895739
https://codereview.chromium.org/514023002/

Not used in production. Log whether a QUIC packet sent was a crypto
packet or not for internal server side tracing.

Merge internal change: 73894063
https://codereview.chromium.org/515003002/

Fix a QUIC bug in which PING frames were not being ACK'd.

Merge internal change: 73837644
https://codereview.chromium.org/512933005/

R=rch@chromium.org

Committed: https://chromium.googlesource.com/chromium/src/+/27f3f1894f09a96112df50fddd32895b4677f949

Review URL: https://codereview.chromium.org/515303003

Cr-Commit-Position: refs/heads/master@{#293030}