Remove unused max_concurrent_streams_limit_ member.

Remove unused max_concurrent_streams_limit_ member.

Remove HttpNetworkSession::Params::spdy_max_concurrent_streams_limit,
SpdySessionPool::max_concurrent_streams_limit_, and
SpdySession::max_concurrent_streams_limit_ members.  Note that
SETTINGS_MAX_CONCURRENT_STREAMS is still limited by kMaxConcurrentStreamLimit,
currently 256.

BUG=481005
Committed: https://crrev.com/48b4c5b02493b72bd7f923cf29c3ede515a1fc1e
Cr-Commit-Position: refs/heads/master@{#327503}

[Bence, 2015-04-29 14:41:37]

bnc@chromium.org changed reviewers:
+ rch@chromium.org

[Bence, 2015-04-29 14:41:38]

Ryan: PTAL.  Thanks.

[Ryan Hamilton, 2015-04-29 15:49:05]

lgtm

[Bence, 2015-04-29 16:17:44]

The CQ bit was checked by bnc@chromium.org

[commit-bot: I haz the power, 2015-04-29 16:18:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1112093002/1

[commit-bot: I haz the power, 2015-04-29 16:21:54]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-29 16:22:48]

Patchset 1 (id:??) landed as
https://crrev.com/48b4c5b02493b72bd7f923cf29c3ede515a1fc1e
Cr-Commit-Position: refs/heads/master@{#327503}