Handle cancelMissedCallsNotification.

Change-Id: Icdbca5371c54af4da098409275092c34c3bddc8b
diff --git a/src/com/android/telecomm/CallsManager.java b/src/com/android/telecomm/CallsManager.java
index cd5cb2a..56e8e51 100644
--- a/src/com/android/telecomm/CallsManager.java
+++ b/src/com/android/telecomm/CallsManager.java
@@ -44,7 +44,7 @@
  * access from other packages specifically refraining from passing the CallsManager instance
  * beyond the com.android.telecomm package boundary.
  */
-public final class CallsManager implements Call.Listener {
+public final class CallsManager extends Call.ListenerBase {
 
     // TODO(santoscordon): Consider renaming this CallsManagerPlugin.
     interface CallsManagerListener {