Update MidiDispatcher to use Mojo Permission Service.

content/browser/web_contents/web_contents_impl.h

Index: content/browser/web_contents/web_contents_impl.h
diff --git a/content/browser/web_contents/web_contents_impl.h b/content/browser/web_contents/web_contents_impl.h
index 08850f19fb3da6c153aeac3d96dd37c7d3a091c1..c809f8d79ec41337aa60be67eb0361b2eb46391e 100644
--- a/content/browser/web_contents/web_contents_impl.h
+++ b/content/browser/web_contents/web_contents_impl.h
@@ -55,7 +55,6 @@ class GeolocationServiceContext;
 class InterstitialPageImpl;
 class JavaScriptDialogManager;
 class ManifestManagerHost;
-class MidiDispatcherHost;
 class PluginContentOriginWhitelist;
 class PowerSaveBlocker;
 class RenderViewHost;
@@ -1213,8 +1212,6 @@ class CONTENT_EXPORT WebContentsImpl
 
   scoped_ptr<GeolocationServiceContext> geolocation_service_context_;
 
-  scoped_ptr<MidiDispatcherHost> midi_dispatcher_host_;
-
   scoped_ptr<ScreenOrientationDispatcherHost>
       screen_orientation_dispatcher_host_;