Allow MessageFilters to restrict listening to specific message classes

content/browser/renderer_host/media/midi_dispatcher_host.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/browser/renderer_host/media/midi_dispatcher_host.h"
 
 #include "base/bind.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/renderer_host/render_view_host_impl.h"
 #include "content/common/media/midi_messages.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "url/gurl.h"
 
 namespace content {
 
 MidiDispatcherHost::MidiDispatcherHost(int render_process_id,
                                        BrowserContext* browser_context)
-    : render_process_id_(render_process_id),
+    : BrowserMessageFilter(MidiMsgStart),
+      render_process_id_(render_process_id),
       browser_context_(browser_context) {
 }
 
 MidiDispatcherHost::~MidiDispatcherHost() {
 }
 
 bool MidiDispatcherHost::OnMessageReceived(const IPC::Message& message,
                                            bool* message_was_ok) {
   bool handled = true;
   IPC_BEGIN_MESSAGE_MAP_EX(MidiDispatcherHost, message, *message_was_ok)
@@ skipping 40 matching lines @@
 }
 void MidiDispatcherHost::WasSysExPermissionGranted(int render_view_id,
                                                    int bridge_id,
                                                    bool success) {
   ChildProcessSecurityPolicyImpl::GetInstance()->GrantSendMidiSysExMessage(
       render_process_id_);
   Send(new MidiMsg_SysExPermissionApproved(render_view_id, bridge_id, success));
 }
 
 }  // namespace content