Landing Recent QUIC Changes.

Landing Recent QUIC Changes.

Simplify QuicUnackedPacketMap's RemovePreviousTransmissions by always
removing all old transmissions.

When truncated acks start arriving, they don't stop until least_unacked
is raised, which takes an entire RTT, so this is the eventual effect of
all those truncated acks.  Instead, remove all of them the first time.

Merge internal change: 74881713
https://codereview.chromium.org/556103002/

Discard old packets from the QuicSentPacketManager which are only
present for RTT purposes(typically acks) when the map exceeds 200 packets.

Merge internal change: 74814618
https://codereview.chromium.org/551223002/

Fix a flaky QUIC end_to_end_test when the socket was suddenly unwritable
and the connection closed, but CanWrite returned true.

Merge internal change: 74798317
https://codereview.chromium.org/550703003/

Fix a crash bug in QuicUnackedPacketMap when truncated acks arrived.

Merge internal change: 74792668
https://codereview.chromium.org/554993002/

Send an ack when it 20 packets have been received since the last ack was
sent.

This allows the peer to discard data from the SentPacketManager.

Merge internal change: 74741188
https://codereview.chromium.org/555653002/

R=rch@chromium.org

Committed: https://crrev.com/e970ae47a0490d1faafd7d6d1c7891a9c901266c
Cr-Commit-Position: refs/heads/master@{#294295}

[ramant (doing other things), 2014-09-10 00:46:50]

On 2014/09/10 00:41:25, ramant wrote:

Hi Ryan,
  This CL and rjshade's CL merges all CL's until sunday. Will merge other CL's
asap.

thanks much
raman

[Ryan Hamilton, 2014-09-10 15:45:20]

lgtm

[ramant (doing other things), 2014-09-11 00:43:34]

The CQ bit was checked by rtenneti@chromium.org

[commit-bot: I haz the power, 2014-09-11 00:55:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/561513003/1

[commit-bot: I haz the power, 2014-09-11 02:02:24]

Committed patchset #1 (id:1) as 3a8a87365c890464ce3f1de607370a88ec4a2a62

[commit-bot: I haz the power, 2014-09-11 03:09:13]

Patchset 1 (id:??) landed as
https://crrev.com/e970ae47a0490d1faafd7d6d1c7891a9c901266c
Cr-Commit-Position: refs/heads/master@{#294295}