[Web MIDI] Use Android MIDI API.

media/midi/midi_manager.h

Index: media/midi/midi_manager.h
diff --git a/media/midi/midi_manager.h b/media/midi/midi_manager.h
index 957c84d427f0dc85b291cd6b9cee188067dca5d7..83d96f2aa5a091e86912d9f87dab72a5927254e0 100644
--- a/media/midi/midi_manager.h
+++ b/media/midi/midi_manager.h
@@ -151,6 +151,9 @@ class MIDI_EXPORT MidiManager {
     return pending_clients_.size();
   }
 
+  const MidiPortInfoList& input_ports() const { return input_ports_; }
+  const MidiPortInfoList& output_ports() const { return output_ports_; }
+
  private:
   void CompleteInitializationInternal(Result result);
   void AddInitialPorts(MidiManagerClient* client);