Revert 273680 "Defer SpdySession destruction to support closing ..."

Revert 273680 "Defer SpdySession destruction to support closing ..."

Referring to https://code.google.com/p/chromium/issues/detail?id=379469
this is causing significant stability on trunk.

> Defer SpdySession destruction to support closing writes
> 
> Replace the STATE_CLOSED availability state with STATE_DRAINING, where:
>  * The read-pump will not run, and no frames can be read.
>  * No new frames may be queued in the sessions's write_queue.
>  * However, the write-pump will continue to run.
> 
> SpdySession's write-pump will destroy the session iff it's draining, the
> write queue is empty and no in-flight writes remain. As this (and
> ~SpdySessionPool()) are now the only locations where SpdySessions may be
> destroyed, session lifetime is more know-able and some WeakPtrs are
> removed.
> 
> Some tests have been updated to include closing RST_STREAMS sent by the
> session. This reflects current behavior. A future CL will add GOAWAY
> frames upon session errors.
> 
> BUG=375033
> 
> Review URL: https://codereview.chromium.org/305823003

TBR=jgraettinger@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=274101

[dxie1, 2014-06-01 02:12:46]

Committed patchset #1 manually as r274101 (tree was closed).