long pendingSize() {
    return pendingSize;
  }
Add this edit to replication queue.
<p/>
The {@code rpcCall} is for retaining the cells if the edit is built within an rpc call and the
rpc call has cell scanner, which is off heap.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/regionreplication/RegionReplicationSink.java