Revert of Add TransportSession interface to prepare for WebRTC-based transport.

Revert of Add TransportSession interface to prepare for WebRTC-based transport. (patchset #4 id:60001 of https://codereview.chromium.org/1420273002/ )

Reason for revert:
Broke android build.

Original issue's description:
> Add TransportSession interface to prepare for WebRTC-based transport.
>
> Previosly JingleSession was responsible to establishing connection
> with the peer and managing list of channels. Now the new
> IceTransportSession class (that implements TransportSession interface)
> is responsible for managing list of channels and so it will be possible
> to add support for WebRTC-based transport by adding another
> TransportSession implementation.
>
> There are no functional changes in this CL.
>
> BUG=547158
>
> Committed: https://crrev.com/7a5351f4c6e407e456978f6599d475616a69fc0b
> Cr-Commit-Position: refs/heads/master@{#356588}

TBR=jamiewalch@chromium.org,sergeyu@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=547158
Committed: https://crrev.com/bedd6b96ef6b16a53432008acc865bfd82fb3e98
Cr-Commit-Position: refs/heads/master@{#356595}

[Georges Khalil, 2015-10-28 18:47:03]

Created Revert of Add TransportSession interface to prepare for WebRTC-based
transport.

[commit-bot: I haz the power, 2015-10-28 18:48:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1413813006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1413813006/1

[commit-bot: I haz the power, 2015-10-28 18:50:00]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-28 18:51:09]

Patchset 1 (id:??) landed as
https://crrev.com/bedd6b96ef6b16a53432008acc865bfd82fb3e98
Cr-Commit-Position: refs/heads/master@{#356595}