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

media/midi/midi_manager_android.cc

 // Copyright 2014 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 "base/memory/scoped_ptr.h"
 #include "media/midi/midi_manager_usb.h"
 #include "media/midi/usb_midi_device_factory_android.h"
 
 namespace media {
 namespace midi {
 
-MidiManager* MidiManager::Create() {
+MidiManager* MidiManager::Create(const CreationOptions& options) {
   return new MidiManagerUsb(

[Takashi Toyoshima, 2015/08/12 04:39:47]

Could it be simply something like this?

if
(base::CommandLine::ForCurrentProcess()->HasSwitch(switches::kUseAndroidMidiApi))
  return new MidiManagerAndroidNative()
else
  return new MidiManagerUsb(...)

[yhirano, 2015/08/12 05:37:05]

Done.

       scoped_ptr<UsbMidiDevice::Factory>(new UsbMidiDeviceFactoryAndroid));
 }
 
 }  // namespace midi
 }  // namespace media