Fix testing issue with DTMF tones

Change-Id: I7832bd23dd5f0ef76833569ee211a9e9804d19b9
diff --git a/tests/src/com/android/telecomm/testapps/TestConnectionManager.java b/tests/src/com/android/telecomm/testapps/TestConnectionManager.java
index 6a8433a..2ee953f 100644
--- a/tests/src/com/android/telecomm/testapps/TestConnectionManager.java
+++ b/tests/src/com/android/telecomm/testapps/TestConnectionManager.java
@@ -133,6 +133,11 @@
             mRemoteConnection.disconnect();
         }
 
+        @Override
+        public void onPlayDtmfTone(char c) {
+            mRemoteConnection.playDtmfTone(c);
+        }
+
         /** ${inheritDoc} */
         @Override
         public void onHold() {