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diff --git a/dom/media/webaudio/blink/HRTFDatabaseLoader.h b/dom/media/webaudio/blink/HRTFDatabaseLoader.h
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+++ b/dom/media/webaudio/blink/HRTFDatabaseLoader.h
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+/*
+ * 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
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
+ *     its contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef HRTFDatabaseLoader_h
+#define HRTFDatabaseLoader_h
+
+#include "nsHashKeys.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/Mutex.h"
+#include "HRTFDatabase.h"
+
+template <class EntryType>
+class nsTHashtable;
+template <class T>
+class nsAutoRef;
+
+namespace WebCore {
+
+// HRTFDatabaseLoader will asynchronously load the default HRTFDatabase in a new
+// thread.
+
+class HRTFDatabaseLoader {
+ public:
+  // Lazily creates a HRTFDatabaseLoader (if not already created) for the given
+  // sample-rate and starts loading asynchronously (when created the first
+  // time). Returns the HRTFDatabaseLoader. Must be called from the main thread.
+  static already_AddRefed<HRTFDatabaseLoader>
+  createAndLoadAsynchronouslyIfNecessary(float sampleRate);
+
+  // AddRef and Release may be called from any thread.
+  void AddRef() {
+#if defined(DEBUG) || defined(NS_BUILD_REFCNT_LOGGING)
+    int count =
+#endif
+        ++m_refCnt;
+    MOZ_ASSERT(count > 0, "invalid ref count");
+    NS_LOG_ADDREF(this, count, "HRTFDatabaseLoader", sizeof(*this));
+  }
+
+  void Release() {
+    // The last reference can't be removed on a non-main thread because
+    // the object can be accessed on the main thread from the hash
+    // table via createAndLoadAsynchronouslyIfNecessary().
+    int count = m_refCnt;
+    MOZ_ASSERT(count > 0, "extra release");
+    // Optimization attempt to possibly skip proxying the release to the
+    // main thread.
+    if (count != 1 && m_refCnt.compareExchange(count, count - 1)) {
+      NS_LOG_RELEASE(this, count - 1, "HRTFDatabaseLoader");
+      return;
+    }
+
+    ProxyRelease();
+  }
+
+  // Returns true once the default database has been completely loaded.
+  bool isLoaded() const;
+
+  // waitForLoaderThreadCompletion() may be called more than once,
+  // on any thread except m_databaseLoaderThread.
+  void waitForLoaderThreadCompletion();
+
+  HRTFDatabase* database() {
+    if (!m_databaseLoaded) {
+      return nullptr;
+    }
+    return m_hrtfDatabase.get();
+  }
+
+  float databaseSampleRate() const { return m_databaseSampleRate; }
+
+  static void shutdown();
+
+  // Called in asynchronous loading thread.
+  void load();
+
+  // Sums the size of all cached database loaders.
+  static size_t sizeOfLoaders(mozilla::MallocSizeOf aMallocSizeOf);
+
+ private:
+  // Both constructor and destructor must be called from the main thread.
+  explicit HRTFDatabaseLoader(float sampleRate);
+  ~HRTFDatabaseLoader();
+
+  size_t sizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const;
+
+  void ProxyRelease();       // any thread
+  void MainThreadRelease();  // main thread only
+  class ProxyReleaseEvent;
+
+  // If it hasn't already been loaded, creates a new thread and initiates
+  // asynchronous loading of the default database. This must be called from the
+  // main thread.
+  void loadAsynchronously();
+
+  // Map from sample-rate to loader.
+  class LoaderByRateEntry : public nsFloatHashKey {
+   public:
+    explicit LoaderByRateEntry(KeyTypePointer aKey)
+        : nsFloatHashKey(aKey),
+          mLoader()  // so PutEntry() will zero-initialize
+    {}
+
+    size_t SizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+      return mLoader ? mLoader->sizeOfIncludingThis(aMallocSizeOf) : 0;
+    }
+
+    // The HRTFDatabaseLoader removes itself from s_loaderMap on destruction.
+    HRTFDatabaseLoader* MOZ_NON_OWNING_REF mLoader;
+  };
+
+  // Keeps track of loaders on a per-sample-rate basis.
+  static nsTHashtable<LoaderByRateEntry>* s_loaderMap;  // singleton
+
+  mozilla::Atomic<int> m_refCnt;
+
+  nsAutoRef<HRTFDatabase> m_hrtfDatabase;
+
+  // Holding a m_threadLock is required when accessing m_databaseLoaderThread.
+  mozilla::Mutex m_threadLock;
+  PRThread* m_databaseLoaderThread MOZ_GUARDED_BY(m_threadLock);
+
+  float m_databaseSampleRate;
+  mozilla::Atomic<bool> m_databaseLoaded;
+};
+
+}  // namespace WebCore
+
+#endif  // HRTFDatabaseLoader_h