Delete unused function SetSessionError.

Delete unused function SetSessionError.

https://webrtc-codereview.appspot.com/47589004/ remove the use.

BUG=505316
Originally reviewed at https://codereview.webrtc.org/1296103002/
TBR=sergeyu@chromium.org

Landed: https://chromium.googlesource.com/external/webrtc/+/dbe5bd9ad58c9d53289ff678b2db54433ac63a07

[Nico, 2015-08-17 18:06:45]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-08-17 18:06:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1299703002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1299703002/1

[commit-bot: I haz the power, 2015-08-17 20:07:05]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-17 20:07:06]

Try jobs failed on following builders:
  android on tryserver.webrtc (JOB_TIMED_OUT, no build URL)
  mac_baremetal on tryserver.webrtc (JOB_TIMED_OUT, no build URL)

[Sergey Ulanov, 2015-08-17 23:06:56]

lgtm

[Sergey Ulanov, 2015-08-17 23:07:20]

The CQ bit was checked by sergeyu@chromium.org

[Sergey Ulanov, 2015-08-17 23:07:23]

The CQ bit was unchecked by sergeyu@chromium.org

[Sergey Ulanov, 2015-08-17 23:10:15]

Looks like you already landed it. Can it be closed?

[Nico, 2015-08-17 23:11:28]

doen