QuicChromiumClientStream handle Read() after trailers are received but not yet delivered

QuicChromiumClientStream handle Read() after trailers are received but not yet delivered

This CL changes QuicChromiumClientStream::Read() to return ERR_IO_PENDNG if
trailers are received but not yet delivered. This CL additionally posts a
OnDataAvailable task when trailers are delivered so as to notify delegate of the
FIN flag.

BUG=652935
NOPRESUBMIT=true
NOTRY=true

TBR=zhongyi@chromium.org

Review-Url: https://codereview.chromium.org/2405523002
Cr-Commit-Position: refs/heads/master@{#424183}
(cherry picked from commit ec0ed02ab197a731d3dcccdd7379c71a057353a1)

[Zhongyi Shi, 2016-10-11 18:20:31]

lgtm

[Zhongyi Shi, 2016-10-11 18:20:32]

lgtm

[xunjieli, 2016-10-11 18:24:30]

On 2016/10/11 18:20:32, Zhongyi Shi wrote:
> lgtm

Thanks! Compiled net_unittests locally and made sure tests are passing.

[xunjieli, 2016-10-11 18:24:33]

The CQ bit was checked by xunjieli@chromium.org

[commit-bot: I haz the power, 2016-10-11 18:25:01]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-10-11 18:27:32]

Committed patchset #1 (id:1)