Basic HTTP pipelining support.

This must be enabled in about:flags. It is naive and assumes all servers correctly implement pipelining. Proxies are not supported.

Immediate future work:
- Integration tests.
- Additional NetLog logging.
- Refactor HttpPipelinedConnectionImpl.

Long term:
- Detect broken transparent proxies.
- Detect and/or mitigate broken servers.
- Buffer HttpPipelinedStream.
- Optimize number of pipelines and their depth.
- Support proxies.

BUG=8991
TEST=net_unittests


Review URL: http://codereview.chromium.org/7289006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@106364 0039d316-1c4b-4281-b951-d872f2087c98
36 files changed