Land Recent QUIC Changes.

Refactor of QUIC's rtt storage and calculation to have a single RttStats
object used by the SentPacketManager, LossDetectionAlgorithms, and SendAlgorithms.

Merge internal change: 62624956
https://codereview.chromium.org/185053006/


QUIC refactor to move the pending_crypto_packet_count_ from the
QuicSentPacketManager to the QuicUnackedPacketMap.

Merge internal change: 62614116
https://codereview.chromium.org/188273003/


QUIC - Fix the spelling error in "frame received." message.

Merge internal change: 62491376
https://codereview.chromium.org/188173003/


Doing a best-effort attempt to send connection close packet for open
quic connection before we call exit().

The actual sending of the connection close is flag protected, though
worst case we'd crash right before exit() anyway.

Merge internal change: 62484710
https://codereview.chromium.org/180953008/


Test only change to QUIC TCPLossAlgorithmTest to ensure the early
retransmit alarms is set for the earliest outstanding packet.

Merge internal change: 62438180
https://codereview.chromium.org/188153003/


CL generated with data from dead-code analysis using Scythe
remove_dead_code tool.

Cleanup of net/quic using Scythe

Merge internal change: 62404986
https://codereview.chromium.org/183683025/


Allow fixed (non-negotiated) values to be sent in QUIC CHLO/SHLO. Also
adds IFCW tag for describing initial flow control window in CHLO/SHLO.

Not used yet.

Merge internal change: 62403534
https://codereview.chromium.org/188183002/


Sync'ing changes with internal tree.

https://codereview.chromium.org/184853014/
Merge internal change: 62295877


Make the VER tag required in QUIC CHLO and SHLO messages.

Merge internal change: 62286870
https://codereview.chromium.org/186313002/

R=rch@chromium.org

Review URL: https://codereview.chromium.org/188333003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255503 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255503