Landing Recent QUIC Changes.

Landing Recent QUIC Changes.

Making the (deprecation-in-progress) congestion field write only.

This is a bit of a hack because technically it's "required" for
QUIC_VERSION_23 but as all the internal servers and all of chrome builds
picking up this change consider the field optional despite the version,
it should just Work (TM).

I was hoping to stop sending the congestion fields for v24 clients but
that is not safe until the internal server fleet doesn't consider it a
required field for negotiated()=true.  Bah.

No longer reading the (deprecated) congestion fields for QUIC.

Merge internal change: 85158634
https://codereview.chromium.org/898233003/

Improving junk packet handling for QUIC by ignoring packets with client
port 0.

Merge internal change: 85067984
https://codereview.chromium.org/885713009/

Removing deprecated flag FLAGS_quic_use_initial_rtt_for_stats.

Merge internal change: 84999682
https://codereview.chromium.org/883393008/

Adding more error logging for failed QUIC writes.

Merge internal change: 84989992
https://codereview.chromium.org/898243002/

Further cleanup to QuicAckNotifier and QuicAckNotifierManager.
No functional change.

Merge internal change: 84784925
https://codereview.chromium.org/880403006/

Remove an unneeded hash_set from QuicAckNotifierManager.
No change in behavior.

Merge internal change: 84637544
https://codereview.chromium.org/872403007/

Minor cleanup and optimization of QuicConnection::IsConnectionClose.

Merge internal change: 84624803
https://codereview.chromium.org/903973002/

Rename QuicAckNotifier's AddSequenceNumber to OnSerializedPacket.
No functional change.

Merge internal change: 84624660
https://codereview.chromium.org/867293004/

R=rch@chromium.org

Committed: https://crrev.com/ff331b65e0aef293ed6f1d0954b83ae17cc66d28
Cr-Commit-Position: refs/heads/master@{#315086}

Committed: https://crrev.com/e6f0c87c4248a1dd48956cf81c2ef56c21ff27db
Cr-Commit-Position: refs/heads/master@{#315115}

[Ryan Hamilton, 2015-02-06 19:11:08]

lgtm

[ramant (doing other things), 2015-02-06 19:31:48]

The CQ bit was checked by rtenneti@chromium.org

[commit-bot: I haz the power, 2015-02-06 19:32:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/903013002/1

[commit-bot: I haz the power, 2015-02-06 19:35:43]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-06 19:36:13]

Patchset 1 (id:??) landed as
https://crrev.com/ff331b65e0aef293ed6f1d0954b83ae17cc66d28
Cr-Commit-Position: refs/heads/master@{#315086}

[ramant (doing other things), 2015-02-06 20:02:53]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/908623002/ by rtenneti@chromium.org.

The reason for reverting is: Broke the build.

[ramant (doing other things), 2015-02-06 21:52:00]

The CQ bit was checked by rtenneti@chromium.org

[commit-bot: I haz the power, 2015-02-06 21:52:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/903013002/1

[commit-bot: I haz the power, 2015-02-06 21:53:55]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-06 21:54:39]

Patchset 1 (id:??) landed as
https://crrev.com/e6f0c87c4248a1dd48956cf81c2ef56c21ff27db
Cr-Commit-Position: refs/heads/master@{#315115}