Creating connections for conference event package participants.

- Add "addExistingConnection" method to connection service which provides
a way for a connection service to notify telecom of a pre-existing
connection (connections are normally created through telecom).
- Modify TelephonyConferenceController to retrieve its state from a
multiparty connection in the conference (in the case of IMS calls, this
would be the ImsCall that manages the conference) instead of just taking
the first one.

Bug: 18057361
Change-Id: I26993aec54ecb0ce90ae6983fd3eed9d8d0a5773
diff --git a/telecomm/java/android/telecom/Conference.java b/telecomm/java/android/telecom/Conference.java
index 15cb786..003d5cd 100644
--- a/telecomm/java/android/telecom/Conference.java
+++ b/telecomm/java/android/telecom/Conference.java
@@ -334,6 +334,19 @@
     }
 
     /**
+     * Retrieves the primary connection associated with the conference.  The primary connection is
+     * the connection from which the conference will retrieve its current state.
+     *
+     * @return The primary connection.
+     */
+    public Connection getPrimaryConnection() {
+        if (mUnmodifiableChildConnections == null || mUnmodifiableChildConnections.isEmpty()) {
+            return null;
+        }
+        return mUnmodifiableChildConnections.get(0);
+    }
+
+    /**
      * Inform this Conference that the state of its audio output has been changed externally.
      *
      * @param state The new audio state.