Provide a default implementation for PeerConnectionInterface::ice_state().

webrtc/api/peerconnectioninterface.h

Index: webrtc/api/peerconnectioninterface.h
diff --git a/webrtc/api/peerconnectioninterface.h b/webrtc/api/peerconnectioninterface.h
index bcb6170c1226ee57f4b26d8855a25ac5dbbd2d5e..8ba2460fa72d81768bc6068c7bee183298457d84 100644
--- a/webrtc/api/peerconnectioninterface.h
+++ b/webrtc/api/peerconnectioninterface.h
@@ -507,7 +507,10 @@ class PeerConnectionInterface : public rtc::RefCountInterface {
   // TODO(bemasc): Remove ice_state when callers are changed to
   // IceConnection/GatheringState.
   // Returns the current IceState.
-  virtual IceState ice_state() = 0;
+  virtual IceState ice_state() {
+      RTC_NOTREACHED();
+    return kIceNew;
+  }
   virtual IceConnectionState ice_connection_state() = 0;
   virtual IceGatheringState ice_gathering_state() = 0;