Revert "Enable MidiManagerWinrt by default on Windows 10"

media/midi/midi_switches.cc

 // 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.
 
 #include "build/build_config.h"
 #include "media/midi/midi_switches.h"
 
 namespace switches {
 
 #if defined(OS_ANDROID)
 // Use Android Midi API for WebMIDI
 const char kUseAndroidMidiApi[] = "use-android-midi-api";
 #endif
 
+}  // namespace switches
+
+namespace midi {
+namespace features {
+
 #if defined(OS_WIN)
-// Disable Windows Runtime Midi API for WebMIDI
-const char kDisableWinrtMidiApi[] = "disable-winrt-midi-api";
+const base::Feature kMidiManagerWinrt{"MidiManagerWinrt",
+                                      base::FEATURE_DISABLED_BY_DEFAULT};
 #endif
 
-}  // namespace switches
+}  // namespace features
+}  // namespace midi