Land Recent QUIC changes.

Fixing minor nits (added using std::pair).

Merge internal change: 53257699

Increasing the maximum tcp congestion window to 200 packets from 100.

Merge internal change: 53185276

Add a DCHECK to ensure the sent packet sequence number never goes down
and separate the send alarm into a send alarm and a resume writes
alarm to be used when the socket is still writable an there may be
more pending data to write.

Merge internal change: 53050471

Merged quic_epoll_connection_helper_test.cc from internal code.

Minor nit fixes.

Merge internal change: 53048224

Move QuicAckNotifierManager from QuicConnection to
QuicSentPacketManager.

Merge internal change: 53036185

R=jar@chromium.org, rch@chromium.org, wtc@chromium.org

Review URL: https://codereview.chromium.org/25443002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226390 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226390