Web MIDI: add dynamic MidiManager instantiation support for Linux

media/midi/midi_manager_usb.h

 // 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.
 
 #ifndef MEDIA_MIDI_MIDI_MANAGER_USB_H_
 #define MEDIA_MIDI_MIDI_MANAGER_USB_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 11 matching lines @@
 #include "media/midi/midi_manager.h"
 #include "media/midi/usb_midi_device.h"
 #include "media/midi/usb_midi_export.h"
 #include "media/midi/usb_midi_input_stream.h"
 #include "media/midi/usb_midi_jack.h"
 #include "media/midi/usb_midi_output_stream.h"
 
 namespace midi {
 
 class MidiScheduler;
+class MidiService;
 
 // MidiManager for USB-MIDI.
 class USB_MIDI_EXPORT MidiManagerUsb
     : public MidiManager,
       public UsbMidiDeviceDelegate,
       NON_EXPORTED_BASE(public UsbMidiInputStream::Delegate) {
  public:
-  explicit MidiManagerUsb(
-      std::unique_ptr<UsbMidiDevice::Factory> device_factory);
+  MidiManagerUsb(MidiService* service,
+                 std::unique_ptr<UsbMidiDevice::Factory> device_factory);
   ~MidiManagerUsb() override;
 
   // MidiManager implementation.
   void StartInitialization() override;
   void Finalize() override;
   void DispatchSendMidiData(MidiManagerClient* client,
                             uint32_t port_index,
                             const std::vector<uint8_t>& data,
                             double timestamp) override;
 
@@ skipping 44 matching lines @@
   // Finalize() on Chrome_IOThread.
   base::Lock scheduler_lock_;
   std::unique_ptr<MidiScheduler> scheduler_;
 
   DISALLOW_COPY_AND_ASSIGN(MidiManagerUsb);
 };
 
 }  // namespace midi
 
 #endif  // MEDIA_MIDI_MIDI_MANAGER_USB_H_