Allow MessageFilters to restrict listening to specific message classes

content/browser/renderer_host/media/media_stream_dispatcher_host.cc

 // Copyright (c) 2012 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/media_stream_dispatcher_host.h"
 
 #include "content/browser/browser_main_loop.h"
 #include "content/common/media/media_stream_messages.h"
 #include "content/common/media/media_stream_options.h"
 #include "url/gurl.h"
 
 namespace content {
 
 MediaStreamDispatcherHost::MediaStreamDispatcherHost(
     int render_process_id,
     ResourceContext* resource_context,
     MediaStreamManager* media_stream_manager)
-    : render_process_id_(render_process_id),
+    : BrowserMessageFilter(MediaStreamMsgStart),
+      render_process_id_(render_process_id),
       resource_context_(resource_context),
       media_stream_manager_(media_stream_manager) {
 }
 
 void MediaStreamDispatcherHost::StreamGenerated(
     int render_view_id,
     int page_request_id,
     const std::string& label,
     const StreamDeviceInfoArray& audio_devices,
     const StreamDeviceInfoArray& video_devices) {
@@ skipping 177 matching lines @@
     int render_view_id,
     const std::string& label) {
   DVLOG(1) << "MediaStreamDispatcherHost::OnCloseDevice("
            << render_view_id << ", "
            << label << ")";
 
   media_stream_manager_->CancelRequest(label);
 }
 
 }  // namespace content