Properly queue messages sent to message ports that are transferred to a service worker.

content/common/message_port_messages.h

 // 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.
 
 // Defines messages between the browser and worker process, as well as between
 // the renderer and worker process.
 
 // Multiply-included message file, hence no include guard.
 
 #include <string>
@@ skipping 65 matching lines @@
 IPC_MESSAGE_CONTROL1(MessagePortHostMsg_QueueMessages,
                      int /* message_port_id */)
 
 // Sends the browser all the queued messages that arrived at this message port
 // after it was sent in a postMessage call.
 // NOTE: MSVS can't compile the macro if std::vector<std::pair<string16, int> >
 // is used, so we typedef it in worker_messages.h.
 IPC_MESSAGE_CONTROL2(MessagePortHostMsg_SendQueuedMessages,
                      int /* message_port_id */,
                      std::vector<QueuedMessage> /* queued_messages */)
+
+// Tells the browser this message port is ready to receive messages. If the
+// browser was holding messages to this port because no destination for the
+// port was available yet this will cause the browser to release those messages.
+IPC_MESSAGE_CONTROL1(MessagePortHostMsg_ReleaseMessages,
+                     int /* message_port_id */)