protected void sendRetryMessage() {
   sendMessage(obtainMessage(RETRY_MESSAGE, null));
 }
 protected void sendFinishMessage() {
   sendMessage(obtainMessage(FINISH_MESSAGE, null));
 }
 protected void sendStartMessage() {
   sendMessage(obtainMessage(START_MESSAGE, null));
 }
 protected void sendFailureMessage(
     int statusCode, Header[] headers, byte[] responseBody, Throwable error) {
   sendMessage(
       obtainMessage(FAILURE_MESSAGE, new Object[] {statusCode, headers, responseBody, error}));
 }
 protected void sendSuccessMessage(int statusCode, Header[] headers, byte[] responseBody) {
   sendMessage(obtainMessage(SUCCESS_MESSAGE, new Object[] {statusCode, headers, responseBody}));
 }
 protected void sendProgressMessage(int bytesWritten, int totalSize) {
   sendMessage(obtainMessage(PROGRESS_MESSAGE, new Object[] {bytesWritten, totalSize}));
 }