Mojo UDP: add a client-side wrapper which handles the client<->server buffering for users.

mojo/services/public/interfaces/network/udp_socket.mojom

 // Copyright 2014 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.
 
 import "mojo/services/public/interfaces/network/net_address.mojom"
 import "mojo/services/public/interfaces/network/network_error.mojom"
 
 module mojo {
 
 // UDPSocket and UDPSocketClient represent a UDP socket and its client. The
@@ skipping 36 matching lines @@
   // requests directly with error code ERR_INSUFFICIENT_RESOURCES and discards
   // those datagrams. If the client wants to avoid such failures, it needs to
   // keep track of how many SendTo() calls are pending and make sure the number
   // doesn't exceed the result of this method.
   NegotiateMaxPendingSendRequests(uint32 requested_size)
       => (uint32 actual_size);
 
   // Notifies that the client is ready to accept |number| of datagrams.
   // Correspondingly, OnReceived() of the UDPSocketClient interface will be
   // called |number| times (errors also count), unless the connection is closed
-  // before that. The socket must be bound.
+  // before that.
   //
   // It is allowed to call this method again before the previous request is
   // completely satisfied. For example:
   //   service->ReceiveMore(3);
   //   ...
   //   // OnReceived() is called.
   //   // OnReceived() is called.
   //   ...
   //   service->ReceiveMore(3);
   //   // The client expects 4 more calls to OnReceived().
@@ skipping 31 matching lines @@
 };
 
 interface UDPSocketClient {
   // On success, |src_addr| and |data| are non-NULL, and |result.code| is a
   // non-negative number indicating how many bytes have been received. On
   // failure, |result.code| is a network error code.
   OnReceived(NetworkError result, NetAddress? src_addr, array<uint8>? data);
 };
 
 }