Convert MIDI permission requests to use WebContents in preparation for switching the code to using RenderFrames.

As part of this, I also simplified the Content API like I did with geolocation in 277038.

BUG=304341
[email protected]
TBR=mkosiba, nasko

Review URL: https://codereview.chromium.org/335993002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@277293 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index f5301e6..9f6ead2 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -36,6 +36,7 @@
 #include "content/browser/geolocation/geolocation_dispatcher_host.h"
 #include "content/browser/host_zoom_map_impl.h"
 #include "content/browser/loader/resource_dispatcher_host_impl.h"
+#include "content/browser/media/midi_dispatcher_host.h"
 #include "content/browser/message_port_message_filter.h"
 #include "content/browser/message_port_service.h"
 #include "content/browser/power_save_blocker_impl.h"
@@ -1094,6 +1095,7 @@
                  NotificationService::AllBrowserContextsAndSources());
 
   geolocation_dispatcher_host_.reset(new GeolocationDispatcherHost(this));
+  midi_dispatcher_host_.reset(new MidiDispatcherHost(this));
 
 #if defined(OS_ANDROID)
   date_time_chooser_.reset(new DateTimeChooserAndroid());