Pepper: Allow plugins to call PPB_UDP_Socket::SendTo multiple times.

ppapi/api/ppb_udp_socket.idl

 /* Copyright 2013 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /**
  * This file defines the <code>PPB_UDPSocket</code> interface.
  */
 
 label Chrome {
@@ skipping 139 matching lines @@
    * @param[in] num_bytes The number of bytes to send.
    * @param[in] addr A <code>PPB_NetAddress</code> resource holding the
    * destination address.
    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
    * completion.
    *
    * @return A non-negative number on success to indicate how many bytes have
    * been sent; otherwise, an error code from <code>pp_errors.h</code>.
    * <code>PP_ERROR_NOACCESS</code> will be returned if the caller doesn't have
    * required permissions.
+   * <code>PP_ERROR_INPROGRESS</code> will be returned if the socket is busy
+   * sending. The caller should wait until a pending send completes before
+   * retrying.
    */
   int32_t SendTo([in] PP_Resource udp_socket,
                  [in] str_t buffer,
                  [in] int32_t num_bytes,
                  [in] PP_Resource addr,
                  [in] PP_CompletionCallback callback);
 
   /**
    * Cancels all pending reads and writes, and closes the socket. Any pending
    * callbacks will still run, reporting <code>PP_ERROR_ABORTED</code> if
@@ skipping 41 matching lines @@
    * completion.
    *
    * @return An int32_t containing an error code from <code>pp_errors.h</code>.
    */
   [version=1.1]
   int32_t SetOption([in] PP_Resource udp_socket,
                     [in] PP_UDPSocket_Option name,
                     [in] PP_Var value,
                     [in] PP_CompletionCallback callback);
 };