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diff --git a/dom/media/webaudio/blink/ReverbAccumulationBuffer.h b/dom/media/webaudio/blink/ReverbAccumulationBuffer.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 ReverbAccumulationBuffer_h
+#define ReverbAccumulationBuffer_h
+
+#include "AlignedTArray.h"
+#include "mozilla/MemoryReporting.h"
+
+namespace WebCore {
+
+// ReverbAccumulationBuffer is a circular delay buffer with one client reading
+// from it and multiple clients writing/accumulating to it at different delay
+// offsets from the read position.  The read operation will zero the memory just
+// read from the buffer, so it will be ready for accumulation the next time
+// around.
+class ReverbAccumulationBuffer {
+ public:
+  ReverbAccumulationBuffer();
+  // Returns false on failure.
+  bool allocate(size_t length);
+
+  // This will read from, then clear-out numberOfFrames
+  void readAndClear(float* destination, size_t numberOfFrames);
+
+  // Each ReverbConvolverStage will accumulate its output at the appropriate
+  // delay from the read position. We need to pass in and update readIndex here,
+  // since each ReverbConvolverStage may be running in a different thread than
+  // the realtime thread calling ReadAndClear() and maintaining m_readIndex
+  void accumulate(const float* source, size_t numberOfFrames, size_t* readIndex,
+                  size_t delayFrames);
+
+  size_t readIndex() const { return m_readIndex; }
+
+  size_t readTimeFrame() const { return m_readTimeFrame; }
+
+  void reset();
+
+  size_t sizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf) const {
+    return m_buffer.ShallowSizeOfExcludingThis(aMallocSizeOf);
+  }
+
+ private:
+  AlignedTArray<float, 16> m_buffer;
+  size_t m_readIndex;
+  size_t m_readTimeFrame;  // for debugging (frame on continuous timeline)
+};
+
+}  // namespace WebCore
+
+#endif  // ReverbAccumulationBuffer_h