Remove the IceTransportInternal2.

Introduing IceTransportInternal2 is a temporary fix to switch the base
class of P2PTransportChannel to IceTransportInternal without breaking
Chromium. It is removed in this CL.

Reland this CL after Chromium doesn't depend on this.

BUG=webrtc:6951

Review-Url: https://codereview.webrtc.org/2632563002
Cr-Commit-Position: refs/heads/master@{#16131}
diff --git a/webrtc/p2p/base/icetransportinternal.h b/webrtc/p2p/base/icetransportinternal.h
index bd3c78a..0593962 100644
--- a/webrtc/p2p/base/icetransportinternal.h
+++ b/webrtc/p2p/base/icetransportinternal.h
@@ -25,9 +25,6 @@
 
 namespace cricket {
 
-class IceTransportInternal;
-typedef IceTransportInternal IceTransportInternal2;
-
 // TODO(zhihuang): replace it with PeerConnectionInterface::IceConnectionState.
 enum class IceTransportState {
   STATE_INIT,