Revert "Enable MidiManagerWinrt by default on Windows 10"

media/midi/midi_switches.h

 // Copyright 2015 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.
 
 // Defines all the "midi" command-line switches.
 
 #ifndef MEDIA_MIDI_MIDI_SWITCHES_H_
 #define MEDIA_MIDI_MIDI_SWITCHES_H_
 
 #include "base/feature_list.h"
 #include "build/build_config.h"
 #include "media/midi/midi_export.h"
 
 namespace switches {
 
 #if defined(OS_ANDROID)
 MIDI_EXPORT extern const char kUseAndroidMidiApi[];
 #endif
 
-#if defined(OS_WIN)
-MIDI_EXPORT extern const char kDisableWinrtMidiApi[];
-#endif
-
 }  // namespace switches
 
+namespace midi {
+namespace features {
+
+#if defined(OS_WIN)
+MIDI_EXPORT extern const base::Feature kMidiManagerWinrt;
+#endif
+
+}  // namespace features
+}  // namespace midi
+
 #endif  // MEDIA_MIDI_MIDI_SWITCHES_H_