Add override declarations to PeerConnectionObserver subclasses, and delete obsolete methods.

webrtc/pc/peerconnectioninterface_unittest.cc

Index: webrtc/pc/peerconnectioninterface_unittest.cc
diff --git a/webrtc/pc/peerconnectioninterface_unittest.cc b/webrtc/pc/peerconnectioninterface_unittest.cc
index dc75ba17b3215d2ffbf57b74321fbdb68c96ba41..5144925c3516b40864fecec9993a42c7d57f9ad3 100644
--- a/webrtc/pc/peerconnectioninterface_unittest.cc
+++ b/webrtc/pc/peerconnectioninterface_unittest.cc
@@ -546,26 +546,6 @@ class MockPeerConnectionObserver : public PeerConnectionObserver {
     EXPECT_EQ(pc_->signaling_state(), new_state);
     state_ = new_state;
   }
-  // TODO(bemasc): Remove this once callers transition to OnIceGatheringChange.
-  virtual void OnStateChange(StateType state_changed) {
-    if (pc_.get() == NULL)
-      return;
-    switch (state_changed) {
-      case kSignalingState:
-        // OnSignalingChange and OnStateChange(kSignalingState) should always
-        // be called approximately simultaneously.  To ease testing, we require
-        // that they always be called in that order.  This check verifies
-        // that OnSignalingChange has just been called.
-        EXPECT_EQ(pc_->signaling_state(), state_);
-        break;
-      case kIceState:
-        ADD_FAILURE();
-        break;
-      default:
-        ADD_FAILURE();
-        break;
-    }
-  }
 
   MediaStreamInterface* RemoteStream(const std::string& label) {
     return remote_streams_->find(label);