Merge "Use thread safe set for RemoteConnection.mListeners" into lmp-dev

import java.util.HashSet;

import java.util.List;

import java.util.Set;

import java.util.concurrent.ConcurrentHashMap;

/**

 * RemoteConnection object used by RemoteConnectionService.

    private IConnectionService mConnectionService;

    private final String mConnectionId;

    private final Set<Listener> mListeners = new HashSet<>();

    private final Set<Listener> mListeners = Collections.newSetFromMap(

            new ConcurrentHashMap<Listener, Boolean>(2));

    private final Set<RemoteConnection> mConferenceableConnections = new HashSet<>();

    private int mState = Connection.State.NEW;