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

media/midi/BUILD.gn

 # 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.
 
 import("//build/config/android/config.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
 import("//testing/test.gni")
 
@@ skipping 60 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",
   ]
 
   configs += [ ":midi_config" ]
 
   defines = [ "MIDI_IMPLEMENTATION" ]
   deps = [
     "//base",
   ]
   libs = []
 
@@ skipping 86 matching lines @@
   }
 
   if (use_alsa && use_udev) {
     sources += [ "midi_manager_alsa_unittest.cc" ]
   }
 
   if (use_x11) {
     deps += [ "//tools/xdisplaycheck" ]
   }
 }