Fixing Coverity bugs (DEAD_CODE and PASS_BY_VALUE)

CIDs 16230, 16439, 16610, 16635

BUG=NONE
TEST=NONE

Review URL: http://codereview.chromium.org/7215029

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@90134 0039d316-1c4b-4281-b951-d872f2087c98
P2PSocketHost* P2PSocketDispatcherHost::LookupSocket(
    int32 routing_id, int socket_id) {
  SocketsMap::iterator it = sockets_.find(
      ExtendedSocketId(routing_id, socket_id));
  if (it == sockets_.end())
    return NULL;
  else
    return it->second;
}

P2PSocketHost* P2PSocketDispatcherHost::LookupSocket(
    int32 routing_id, int socket_id) {
  SocketsMap::iterator it = sockets_.find(
      ExtendedSocketId(routing_id, socket_id));
  if (it == sockets_.end())
    return NULL;
  else
    return it->second;
}
