Re-land: Ensure that ArrayBuffers actively being used by the Web Audio API cannot be neutered

Source/modules/webaudio/AudioBuffer.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 49 matching lines @@
 AudioBuffer::AudioBuffer(unsigned numberOfChannels, size_t numberOfFrames, float sampleRate)
     : m_gain(1.0)
     , m_sampleRate(sampleRate)
     , m_length(numberOfFrames)
 {
     ScriptWrappable::init(this);
     m_channels.reserveCapacity(numberOfChannels);
 
     for (unsigned i = 0; i < numberOfChannels; ++i) {
         RefPtr<Float32Array> channelDataArray = Float32Array::create(m_length);
+        channelDataArray->setNeuterable(false);
         m_channels.append(channelDataArray);
     }
 }
 
 AudioBuffer::AudioBuffer(AudioBus* bus)
     : m_gain(1.0)
     , m_sampleRate(bus->sampleRate())
     , m_length(bus->length())
 {
     ScriptWrappable::init(this);
     // Copy audio data from the bus to the Float32Arrays we manage.
     unsigned numberOfChannels = bus->numberOfChannels();
     m_channels.reserveCapacity(numberOfChannels);
     for (unsigned i = 0; i < numberOfChannels; ++i) {
         RefPtr<Float32Array> channelDataArray = Float32Array::create(m_length);
+        channelDataArray->setNeuterable(false);
         channelDataArray->setRange(bus->channel(i)->data(), m_length, 0);
         m_channels.append(channelDataArray);
     }
 }
 
 void AudioBuffer::releaseMemory()
 {
     m_channels.clear();
 }
 
-Float32Array* AudioBuffer::getChannelData(unsigned channelIndex, ExceptionState& es)
+PassRefPtr<Float32Array> AudioBuffer::getChannelData(unsigned channelIndex, ExceptionState& es)
 {
     if (channelIndex >= m_channels.size()) {
         es.throwDOMException(SyntaxError);
         return 0;
     }
 
-    return m_channels[channelIndex].get();
+    Float32Array* channelData = m_channels[channelIndex].get();
+    return Float32Array::create(channelData->buffer(), channelData->byteOffset(), channelData->length());
 }
 
 Float32Array* AudioBuffer::getChannelData(unsigned channelIndex)
 {
     if (channelIndex >= m_channels.size())
         return 0;
 
     return m_channels[channelIndex].get();
 }
 
 void AudioBuffer::zero()
 {
     for (unsigned i = 0; i < m_channels.size(); ++i) {
         if (getChannelData(i))
             getChannelData(i)->zeroRange(0, length());
     }
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)