Oilpan: Don't destruct HRTFDatabaseLoader::m_thread during a sweeping phase

Source/platform/audio/HRTFDatabaseLoader.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 15 matching lines @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 
 #if ENABLE(WEB_AUDIO)
 
 #include "platform/audio/HRTFDatabaseLoader.h"
 
 #include "platform/Task.h"
+#include "platform/TaskSynchronizer.h"
 #include "public/platform/Platform.h"
 #include "wtf/MainThread.h"
 
 namespace blink {
 
 typedef HeapHashMap<double, WeakMember<HRTFDatabaseLoader> > LoaderMap;
 
 static LoaderMap& loaderMap()
 {
     DEFINE_STATIC_LOCAL(Persistent<LoaderMap>, map, (new LoaderMap));
@@ skipping 18 matching lines @@
 
 HRTFDatabaseLoader::HRTFDatabaseLoader(float sampleRate)
     : m_databaseSampleRate(sampleRate)
 {
     ASSERT(isMainThread());
 }
 
 HRTFDatabaseLoader::~HRTFDatabaseLoader()
 {
     ASSERT(isMainThread());
-    waitForLoaderThreadCompletion();
+    ASSERT(!m_thread);
 }
 
-void HRTFDatabaseLoader::load()
+void HRTFDatabaseLoader::loadTask()
 {
     ASSERT(!isMainThread());
     m_thread->attachGC();
 
     {
         MutexLocker locker(m_lock);
         if (!m_hrtfDatabase) {
             // Load the default HRTF database.
             m_hrtfDatabase = HRTFDatabase::create(m_databaseSampleRate);
         }
     }
 
     m_thread->detachGC();
 }
 
 void HRTFDatabaseLoader::loadAsynchronously()
 {
     ASSERT(isMainThread());
 
     MutexLocker locker(m_lock);
     if (!m_hrtfDatabase && !m_thread) {
         // Start the asynchronous database loading process.
         m_thread = WebThreadSupportingGC::create("HRTF database loader");
-        m_thread->postTask(new Task(WTF::bind(&HRTFDatabaseLoader::load, this)));
+        m_thread->postTask(new Task(WTF::bind(&HRTFDatabaseLoader::loadTask, this)));
     }
 }
 
 bool HRTFDatabaseLoader::isLoaded()
 {
     MutexLocker locker(m_lock);
     return m_hrtfDatabase;
 }
 
+// This cleanup task is needed just to make sure that the loader thread finishes
+// the load task and thus the loader thread doesn't touch m_thread any more.
+void HRTFDatabaseLoader::cleanupTask(TaskSynchronizer* sync)
+{
+    sync->taskCompleted();
+}
+
 void HRTFDatabaseLoader::waitForLoaderThreadCompletion()
 {
+    if (!m_thread)
+        return;
+
+    TaskSynchronizer sync;
+    m_thread->postTask(new Task(WTF::bind(&HRTFDatabaseLoader::cleanupTask, this, &sync)));
+    sync.waitForTaskCompletion();
     m_thread.clear();
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)