Revert 207992: This looks like a reland of r207983, which was reverted in

trunk/src/content/renderer/render_thread_impl.cc

Index: trunk/src/content/renderer/render_thread_impl.cc
===================================================================
--- trunk/src/content/renderer/render_thread_impl.cc	(revision 207994)
+++ trunk/src/content/renderer/render_thread_impl.cc	(working copy)
@@ -65,7 +65,6 @@
 #include "content/renderer/media/audio_renderer_mixer_manager.h"
 #include "content/renderer/media/media_stream_center.h"
 #include "content/renderer/media/media_stream_dependency_factory.h"
-#include "content/renderer/media/midi_message_filter.h"
 #include "content/renderer/media/peer_connection_tracker.h"
 #include "content/renderer/media/video_capture_impl_manager.h"
 #include "content/renderer/media/video_capture_message_filter.h"
@@ -369,9 +368,6 @@
   audio_message_filter_ = new AudioMessageFilter(GetIOMessageLoopProxy());
   AddFilter(audio_message_filter_.get());
 
-  midi_message_filter_ = new MIDIMessageFilter(GetIOMessageLoopProxy());
-  AddFilter(midi_message_filter_.get());
-
   AddFilter(new IndexedDBMessageFilter);
 
   GetContentClient()->renderer()->RenderThreadStarted();