Fix issue where self-managed calls play ringtone.

If the default dialer doesn't handle ringtones, selfmanaged calls will
play the system ringtone.

Test: Manual
Bug: 36866764
Change-Id: I5392333005d30b422aadb37e2a7578597fcd9760
diff --git a/src/com/android/server/telecom/Ringer.java b/src/com/android/server/telecom/Ringer.java
index c6056fa..c5817e7 100644
--- a/src/com/android/server/telecom/Ringer.java
+++ b/src/com/android/server/telecom/Ringer.java
@@ -116,6 +116,11 @@
             return isRingerAudible;
         }
 
+        if (foregroundCall.isSelfManaged()) {
+            Log.addEvent(foregroundCall, LogUtils.Events.SKIP_RINGING, "Self-managed");
+            return false;
+        }
+
         stopCallWaiting();
 
         if (!shouldRingForContact(foregroundCall.getContactUri())) {
@@ -161,6 +166,11 @@
             return;
         }
 
+        if (call.isSelfManaged()) {
+            Log.addEvent(call, LogUtils.Events.SKIP_RINGING, "Self-managed");
+            return;
+        }
+
         Log.v(this, "Playing call-waiting tone.");
 
         stopRinging();