Web MIDI: add MidiScheduler for send() with timestamp

media/midi/midi_manager_usb.h

Index: media/midi/midi_manager_usb.h
diff --git a/media/midi/midi_manager_usb.h b/media/midi/midi_manager_usb.h
index ea9b5890e595dc7d005e02fb763fcfacaf98673a..417aac57910f9b7dbc910ed148ff3d19b785e1e0 100644
--- a/media/midi/midi_manager_usb.h
+++ b/media/midi/midi_manager_usb.h
@@ -23,6 +23,8 @@
 
 namespace media {
 
+class MidiScheduler;
+
 // MidiManager for USB-MIDI.
 class MEDIA_EXPORT MidiManagerUsb : public MidiManager,
                                     public UsbMidiDeviceDelegate,
@@ -81,6 +83,8 @@ class MEDIA_EXPORT MidiManagerUsb : public MidiManager,
   // A map from <endpoint_number, cable_number> to the index of input jacks.
   base::hash_map<std::pair<int, int>, size_t> input_jack_dictionary_;
 
+  scoped_ptr<MidiScheduler> scheduler_;
+
   DISALLOW_COPY_AND_ASSIGN(MidiManagerUsb);
 };