Decouple MIDIAccess initialization from MIDIAccess class.

Source/web/WebMIDIClientMock.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 36 matching lines @@
     m_clientMock->setSysexPermission(allowed);
 }
 
 void WebMIDIClientMock::resetMock()
 {
     m_clientMock->resetMock();
 }
 
 void WebMIDIClientMock::requestSysexPermission(const WebMIDIPermissionRequest& request)
 {
-    m_clientMock->requestSysexPermission(request.midiAccess());
+    m_clientMock->requestSysexPermission(request.midiAccessInitializer());
 }
 
 void WebMIDIClientMock::cancelSysexPermissionRequest(const WebMIDIPermissionRequest& request)
 {
-    m_clientMock->cancelSysexPermissionRequest(request.midiAccess());
+    m_clientMock->cancelSysexPermissionRequest(request.midiAccessInitializer());
 }
 
 void WebMIDIClientMock::reset()
 {
     m_clientMock.reset(0);
 }
 
 } // blink