Delete deprecated PeerConnection methods, and corresponding using declarations.

webrtc/api/peerconnectioninterface_unittest.cc

Index: webrtc/api/peerconnectioninterface_unittest.cc
diff --git a/webrtc/api/peerconnectioninterface_unittest.cc b/webrtc/api/peerconnectioninterface_unittest.cc
index 2da3755fcb7eef39f4491f2edfe1fe9790a5bb78..e50d77b7ac8e899462d308c9248c7a998518b525 100644
--- a/webrtc/api/peerconnectioninterface_unittest.cc
+++ b/webrtc/api/peerconnectioninterface_unittest.cc
@@ -507,13 +507,6 @@ class MockTrackObserver : public ObserverInterface {
 
 class MockPeerConnectionObserver : public PeerConnectionObserver {
  public:
-  // We need these using declarations because there are two versions of each of
-  // the below methods and we only override one of them.
-  // TODO(deadbeef): Remove once there's only one version of the methods.
-  using PeerConnectionObserver::OnAddStream;
-  using PeerConnectionObserver::OnRemoveStream;
-  using PeerConnectionObserver::OnDataChannel;
-
   MockPeerConnectionObserver() : remote_streams_(StreamCollection::Create()) {}
   virtual ~MockPeerConnectionObserver() {
   }