Added support for mid-call enabled SRVCC conference call

When TelephonyConnection is created for an unknown connection,
the recalculation of conference participants have to be
retriggered. This is because, unless that TelephonyConnection is
added to ConnectionService, it cannot be added as part of a
conference call in CallsManager.

Change-Id: Ic9359104f02eddff655d84fd25f5c28c9158e5f4

telecomm/java/android/telecom/ConnectionService.java

@@ -655,6 +655,9 @@ public abstract class ConnectionService extends Service {
                         connection.getDisconnectCause(),
                         createIdList(connection.getConferenceables()),
                         connection.getExtras()));
+        if (isUnknown) {
+            triggerConferenceRecalculate();
+        }
     }
 
     private void abort(String callId) {
@@ -1013,6 +1016,16 @@ public abstract class ConnectionService extends Service {
         return null;
     }
 
+    /**
+     * Trigger recalculate functinality for conference calls. This is used when a Telephony
+     * Connection is part of a conference controller but is not yet added to Connection
+     * Service and hence cannot be added to the conference call.
+     *
+     * @hide
+     */
+    public void triggerConferenceRecalculate() {
+    }
+
     /**
      * Create a {@code Connection} given an outgoing request. This is used to initiate new
      * outgoing calls.