Revert of Make P2PTransportChannel inherit from IceTransportInternal.

Revert of Make P2PTransportChannel inherit from IceTransportInternal. (patchset #3 id:80001 of https://codereview.webrtc.org/2590063002/ )

Reason for revert:
Breaks Chromium WebRTC FYI bots:
https://build.chromium.org/p/chromium.webrtc.fyi/builders/Linux%20Builder/builds/12337
The error was masked by another breaking change that was committer earlier. This is the first build showing the error.

Original issue's description:
> Make P2PTransportChannel inherit from IceTransportInternal.
> 
> Make P2PTransportChannel inherit from IceTransportInternal instead of
> TransportChannelImpl and TransportChannel, so that the DTLS-related methods can
> be separated from P2PTransportChannel.
> 
> BUG=none
> 
> Review-Url: https://codereview.webrtc.org/2590063002
> Cr-Commit-Position: refs/heads/master@{#15743}
> Committed: https://chromium.googlesource.com/external/webrtc/+/12749d89d9f004cc1961aa6ece6600cc14c57ac5

TBR=deadbeef@webrtc.org,zhihuang@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=none

Review-Url: https://codereview.webrtc.org/2594343002
Cr-Commit-Position: refs/heads/master@{#15751}
Committed: https://chromium.googlesource.com/external/webrtc/+/c37ad499dac38d992a09e3b3565a366b283a2521

[kjellander_webrtc, 2016-12-22 07:51:40]

The CQ bit was checked by kjellander@webrtc.org

[kjellander_webrtc, 2016-12-22 07:51:41]

Created Revert of Make P2PTransportChannel inherit from IceTransportInternal.

[commit-bot: I haz the power, 2016-12-22 07:51:53]

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

[commit-bot: I haz the power, 2016-12-22 07:52:01]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1482393100944690, "parent_rev":
"d943c4845439aab311212b881d05ca0f2bb493f8", "commit_rev":
"c37ad499dac38d992a09e3b3565a366b283a2521"}

[commit-bot: I haz the power, 2016-12-22 07:52:03]

Description was changed from

==========
Revert of Make P2PTransportChannel inherit from IceTransportInternal. (patchset
#3 id:80001 of https://codereview.webrtc.org/2590063002/ )

Reason for revert:
Breaks Chromium WebRTC FYI bots:
https://build.chromium.org/p/chromium.webrtc.fyi/builders/Linux%20Builder/bui...
The error was masked by another breaking change that was committer earlier. This
is the first build showing the error.

Original issue's description:
> Make P2PTransportChannel inherit from IceTransportInternal.
> 
> Make P2PTransportChannel inherit from IceTransportInternal instead of
> TransportChannelImpl and TransportChannel, so that the DTLS-related methods
can
> be separated from P2PTransportChannel.
> 
> BUG=none
> 
> Review-Url: https://codereview.webrtc.org/2590063002
> Cr-Commit-Position: refs/heads/master@{#15743}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/12749d89d9f004cc1961aa6ec...

TBR=deadbeef@webrtc.org,zhihuang@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=none
==========

to

==========
Revert of Make P2PTransportChannel inherit from IceTransportInternal. (patchset
#3 id:80001 of https://codereview.webrtc.org/2590063002/ )

Reason for revert:
Breaks Chromium WebRTC FYI bots:
https://build.chromium.org/p/chromium.webrtc.fyi/builders/Linux%20Builder/bui...
The error was masked by another breaking change that was committer earlier. This
is the first build showing the error.

Original issue's description:
> Make P2PTransportChannel inherit from IceTransportInternal.
> 
> Make P2PTransportChannel inherit from IceTransportInternal instead of
> TransportChannelImpl and TransportChannel, so that the DTLS-related methods
can
> be separated from P2PTransportChannel.
> 
> BUG=none
> 
> Review-Url: https://codereview.webrtc.org/2590063002
> Cr-Commit-Position: refs/heads/master@{#15743}
> Committed:
https://chromium.googlesource.com/external/webrtc/+/12749d89d9f004cc1961aa6ec...

TBR=deadbeef@webrtc.org,zhihuang@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=none

Review-Url: https://codereview.webrtc.org/2594343002
Cr-Commit-Position: refs/heads/master@{#15751}
Committed:
https://chromium.googlesource.com/external/webrtc/+/c37ad499dac38d992a09e3b35...
==========

[commit-bot: I haz the power, 2016-12-22 07:52:04]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/external/webrtc/+/c37ad499dac38d992a09e3b35...

[kjellander_webrtc, 2016-12-22 09:15:14]

On 2016/12/22 07:52:04, commit-bot: I haz the power wrote:
> Committed patchset #1 (id:1) as
>
https://chromium.googlesource.com/external/webrtc/+/c37ad499dac38d992a09e3b35...

Follow-up: This greened up all the builds, so the revert was correct.
For relanding, please make changes that aren't breaking the API + run Chromium
trybots for the WebRTC CL as mentioned at
https://webrtc.org/contributing/#tryjobs-on-chromium-trybots