[not for review] Web MIDI: new backend to support dynamic instantiation on Windows

media/midi/midi_manager.cc

 // Copyright (c) 2013 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.h"
 
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
@@ skipping 167 matching lines @@
                                        const std::vector<uint8_t>& data,
                                        double timestamp) {
   NOTREACHED();
 }
 
 void MidiManager::StartInitialization() {
   CompleteInitialization(Result::NOT_SUPPORTED);
 }
 
 void MidiManager::CompleteInitialization(Result result) {
-  base::AutoLock auto_lock(lock_);
-  if (session_thread_runner_) {
-    session_thread_runner_->PostTask(
-        FROM_HERE, base::Bind(&MidiManager::CompleteInitializationInternal,
-                              base::Unretained(this), result));
+  bool complete_asynchronously = false;
+  {
+    base::AutoLock auto_lock(lock_);
+    if (session_thread_runner_) {
+      if (session_thread_runner_->BelongsToCurrentThread()) {
+        complete_asynchronously = true;
+      } else {
+        session_thread_runner_->PostTask(
+            FROM_HERE, base::Bind(&MidiManager::CompleteInitializationInternal,
+                                  base::Unretained(this), result));
+      }
+    }
   }
+  if (complete_asynchronously)
+    CompleteInitializationInternal(result);
 }
 
 void MidiManager::AddInputPort(const MidiPortInfo& info) {
   ReportUsage(Usage::INPUT_PORT_ADDED);
   base::AutoLock auto_lock(lock_);
   input_ports_.push_back(info);
   for (auto* client : clients_)
     client->AddInputPort(info);
 }
 
@@ skipping 70 matching lines @@
   Finalize();
   base::AutoLock auto_lock(lock_);
   finalized_ = true;
 
   // Detach all clients so that they do not call MidiManager methods any more.
   for (auto* client : clients_)
     client->Detach();
 }
 
 }  // namespace midi