[WebMIDI] Remove not needed CancelPermission IPC message.

content/common/media/midi_messages.h

 // Copyright (c) 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.
 
 // IPC messages for access to MIDI hardware.
 // Multiply-included message file, hence no include guard.
 
 #include "base/basictypes.h"
 #include "content/common/content_export.h"
 #include "ipc/ipc_message_macros.h"
@@ skipping 16 matching lines @@
 IPC_ENUM_TRAITS_MAX_VALUE(media::MidiResult, media::MIDI_RESULT_LAST)
 
 // Messages for IPC between MidiDispatcher and MidiDispatcherHost.
 
 // Renderer request to browser for using system exclusive messages.
 IPC_MESSAGE_ROUTED3(MidiHostMsg_RequestSysExPermission,
                     int /* client id */,
                     GURL /* origin */,
                     bool /* user_gesture */)
 
-// Renderer request to browser for canceling a previous permission request.
-IPC_MESSAGE_ROUTED2(MidiHostMsg_CancelSysExPermissionRequest,
-                     int /* bridge_id */,
-                     GURL /* GURL of the frame */)
-
 // Messages sent from the browser to the renderer.
 
 IPC_MESSAGE_ROUTED2(MidiMsg_SysExPermissionApproved,
                     int /* client id */,
                     bool /* is_allowed */)
 
 // Messages for IPC between MidiMessageFilter and MidiHost.
 
 // Renderer request to browser for access to MIDI services.
 IPC_MESSAGE_CONTROL1(MidiHostMsg_StartSession,
@@ skipping 12 matching lines @@
                      media::MidiPortInfoList /* input ports */,
                      media::MidiPortInfoList /* output ports */)
 
 IPC_MESSAGE_CONTROL3(MidiMsg_DataReceived,
                      uint32 /* port */,
                      std::vector<uint8> /* data */,
                      double /* timestamp */)
 
 IPC_MESSAGE_CONTROL1(MidiMsg_AcknowledgeSentData,
                      uint32 /* bytes sent */)