Implement midi permissions on top of the new common permission classes

content/renderer/media/midi_dispatcher.cc

 // 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.
 
 #include "content/renderer/media/midi_dispatcher.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "content/common/media/midi_messages.h"
 #include "third_party/WebKit/public/platform/WebString.h"
@@ skipping 32 matching lines @@
 }
 
 void MidiDispatcher::cancelSysexPermissionRequest(
     const WebMIDIPermissionRequest& request) {
   for (Requests::iterator it(&requests_); !it.IsAtEnd(); it.Advance()) {
     WebMIDIPermissionRequest* value = it.GetCurrentValue();
     if (value->equals(request)) {
       base::string16 origin = request.securityOrigin().toString();
       Send(new MidiHostMsg_CancelSysExPermissionRequest(
           routing_id(), it.GetCurrentKey(), GURL(origin)));
-      requests_.Remove(it.GetCurrentKey());
+      // The request will be removed by OnSysExPermissionApproved once
+      // the blink MIDIAccessInitializer object is deleted.
       break;
     }
   }
 }
 
 void MidiDispatcher::OnSysExPermissionApproved(int bridge_id,
                                                bool is_allowed) {
   // |request| can be NULL when the request is canceled.
   WebMIDIPermissionRequest* request = requests_.Lookup(bridge_id);
   if (!request)
     return;
   request->setIsAllowed(is_allowed);
   requests_.Remove(bridge_id);
 }
 
 }  // namespace content