MidiScheduler binds to task runner of constructing thread

media/midi/midi_manager_usb.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 "media/midi/midi_manager_usb.h"
 
 #include <utility>
 
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/stringprintf.h"
 #include "media/midi/midi_scheduler.h"
 #include "media/midi/usb_midi_descriptor_parser.h"
 
 namespace media {
 namespace midi {
 
 MidiManagerUsb::MidiManagerUsb(std::unique_ptr<UsbMidiDevice::Factory> factory)
     : device_factory_(std::move(factory)) {}
 
 MidiManagerUsb::~MidiManagerUsb() {
+  base::AutoLock auto_lock(scheduler_lock_);
+  CHECK(!scheduler_);
 }
 
 void MidiManagerUsb::StartInitialization() {
   Initialize(
       base::Bind(&MidiManager::CompleteInitialization, base::Unretained(this)));
 }
 
+void MidiManagerUsb::Finalize() {
+  // Destruct MidiScheduler on Chrome_IOThread.
+  base::AutoLock auto_lock(scheduler_lock_);
+  scheduler_.reset();
+}
+
 void MidiManagerUsb::Initialize(base::Callback<void(Result result)> callback) {
   initialize_callback_ = callback;
-  scheduler_.reset(new MidiScheduler(this));
+
+  {
+    base::AutoLock auto_lock(scheduler_lock_);
+    scheduler_.reset(new MidiScheduler(this));
+  }
+
   // This is safe because EnumerateDevices cancels the operation on destruction.
   device_factory_->EnumerateDevices(
       this,
       base::Bind(&MidiManagerUsb::OnEnumerateDevicesDone,
                  base::Unretained(this)));
 }
 
 void MidiManagerUsb::DispatchSendMidiData(MidiManagerClient* client,
                                           uint32_t port_index,
                                           const std::vector<uint8_t>& data,
@@ skipping 106 matching lines @@
       input_stream_->Add(jacks[j]);
       AddInputPort(MidiPortInfo(id, manufacturer, product_name, version,
                                 MIDI_PORT_OPENED));
     }
   }
   return true;
 }
 
 }  // namespace midi
 }  // namespace media