[WebMIDI] Add "use-android-midi-api" flag for Android M+ devices.

media/midi/midi.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'conditions': [
       ['(OS=="linux" or OS=="freebsd" or OS=="solaris") and (embedded!=1 or (chromecast==1 and target_arch!="arm"))', {
         'use_alsa%': 1,
@@ skipping 41 matching lines @@
         'midi_manager_win.cc',
         'midi_manager_win.h',
         'midi_message_queue.cc',
         'midi_message_queue.h',
         'midi_message_util.cc',
         'midi_message_util.h',
         'midi_port_info.cc',
         'midi_port_info.h',
         'midi_scheduler.cc',
         'midi_scheduler.h',
+        'midi_switches.cc',
+        'midi_switches.h',
         'usb_midi_device_android.cc',
         'usb_midi_device_android.h',
         'usb_midi_device_factory_android.cc',
         'usb_midi_device_factory_android.h',
       ],
       'direct_dependent_settings': {
         'include_dirs': [
           '../..',
         ],
       },
@@ skipping 157 matching lines @@
             '../../build/isolate.gypi',
           ],
           'sources': [
             'midi_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }