Don't start ringback until CallService ACK

Only start playing the ringback tone once a CallService has
acknowledged that it can be handling the call.

Bug: 13902624

Change-Id: I702dff71e4042ae87dd9aa2c46d53e9bdd66f321
diff --git a/src/com/android/telecomm/CallsManager.java b/src/com/android/telecomm/CallsManager.java
index 8e81752..5c95211 100644
--- a/src/com/android/telecomm/CallsManager.java
+++ b/src/com/android/telecomm/CallsManager.java
@@ -110,8 +110,7 @@
         mListeners.add(new CallLogManager(app));
         mListeners.add(new PhoneStateBroadcaster());
         mListeners.add(new InCallController());
-        mListeners.add(
-                new Ringer(mCallAudioManager, this, playerFactory, TelecommApp.getInstance()));
+        mListeners.add(new Ringer(mCallAudioManager, this, playerFactory, app));
         mListeners.add(new RingbackPlayer(this, playerFactory));
         mListeners.add(new InCallToneMonitor(playerFactory, this));
         mListeners.add(mCallAudioManager);