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diff --git a/dom/media/webaudio/blink/ReverbConvolverStage.cpp b/dom/media/webaudio/blink/ReverbConvolverStage.cpp
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+++ b/dom/media/webaudio/blink/ReverbConvolverStage.cpp
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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.
+ */
+
+#include "ReverbConvolverStage.h"
+
+#include "ReverbAccumulationBuffer.h"
+#include "ReverbConvolver.h"
+#include "ReverbInputBuffer.h"
+#include "mozilla/PodOperations.h"
+
+using namespace mozilla;
+
+namespace WebCore {
+
+ReverbConvolverStage::ReverbConvolverStage(
+    const float* impulseResponse, size_t, size_t reverbTotalLatency,
+    size_t stageOffset, size_t stageLength, size_t fftSize, size_t renderPhase,
+    ReverbAccumulationBuffer* accumulationBuffer)
+    : m_accumulationBuffer(accumulationBuffer),
+      m_accumulationReadIndex(0),
+      m_inputReadIndex(0) {
+  MOZ_ASSERT(impulseResponse);
+  MOZ_ASSERT(accumulationBuffer);
+
+  m_fftKernel = MakeUnique<FFTBlock>(fftSize);
+  m_fftKernel->PadAndMakeScaledDFT(impulseResponse + stageOffset, stageLength);
+  m_fftConvolver = MakeUnique<FFTConvolver>(fftSize, renderPhase);
+
+  // The convolution stage at offset stageOffset needs to have a corresponding
+  // delay to cancel out the offset.
+  size_t totalDelay = stageOffset + reverbTotalLatency;
+
+  // But, the FFT convolution itself incurs latency, so subtract this out...
+  size_t fftLatency = m_fftConvolver->latencyFrames();
+  MOZ_ASSERT(totalDelay >= fftLatency);
+  totalDelay -= fftLatency;
+
+  m_postDelayLength = totalDelay;
+}
+
+size_t ReverbConvolverStage::sizeOfIncludingThis(
+    mozilla::MallocSizeOf aMallocSizeOf) const {
+  size_t amount = aMallocSizeOf(this);
+
+  if (m_fftKernel) {
+    amount += m_fftKernel->SizeOfIncludingThis(aMallocSizeOf);
+  }
+
+  if (m_fftConvolver) {
+    amount += m_fftConvolver->sizeOfIncludingThis(aMallocSizeOf);
+  }
+
+  return amount;
+}
+
+void ReverbConvolverStage::processInBackground(ReverbConvolver* convolver) {
+  ReverbInputBuffer* inputBuffer = convolver->inputBuffer();
+  float* source =
+      inputBuffer->directReadFrom(&m_inputReadIndex, WEBAUDIO_BLOCK_SIZE);
+  process(source);
+}
+
+void ReverbConvolverStage::process(const float* source) {
+  MOZ_ASSERT(source);
+  if (!source) return;
+
+  // Now, run the convolution (into the delay buffer).
+  // An expensive FFT will happen every fftSize / 2 frames.
+  const float* output = m_fftConvolver->process(m_fftKernel.get(), source);
+
+  // Now accumulate into reverb's accumulation buffer.
+  m_accumulationBuffer->accumulate(output, WEBAUDIO_BLOCK_SIZE,
+                                   &m_accumulationReadIndex, m_postDelayLength);
+}
+
+}  // namespace WebCore