Web Audio: Various code cleanup

- Use references instead of pointers if they are obviously not null.

- Remove AudioBufferSourceHandler::start(ExceptionState&)
  It just call another overload.  A callsite can call it.

- Remove redundant isContextClosed check in AudioContext::create*().
  If a factory function calls another factory function, isContextClosed was
  checked multiple times.

- Remove redundant hadException check in AudioContext::createDelay
  DelayNode::create returns nullptr in that case.

- Fold DeferredTaskHandler::disposeOutputs into AudioHandler::dispose

- Remove obsolete comment in DeferredTaskHandler.

- Remove |autoInitialize| argument of BiquadProcessor constructor
  It's always false.

BUG=

Review URL: https://codereview.chromium.org/1059763004

git-svn-id: svn://svn.chromium.org/blink/trunk@193242 bbb929c8-8fbe-4397-9dbb-9b2b20218538

41 files changed, 107 insertions, 157 deletions

diff --git a/third_party/WebKit/Source/modules/webaudio/AnalyserNode.cpp b/third_party/WebKit/Source/modules/webaudio/AnalyserNode.cpp
index 075ae43..43903af 100644
--- a/third_party/WebKit/Source/modules/webaudio/AnalyserNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AnalyserNode.cpp
@@ -123,9 +123,9 @@ AnalyserNode::AnalyserNode(AudioContext& context, float sampleRate)
     setHandler(new AnalyserHandler(*this, sampleRate));
 }
 
-AnalyserNode* AnalyserNode::create(AudioContext* context, float sampleRate)
+AnalyserNode* AnalyserNode::create(AudioContext& context, float sampleRate)
 {
-    return new AnalyserNode(*context, sampleRate);
+    return new AnalyserNode(context, sampleRate);
 }
 
 AnalyserHandler& AnalyserNode::analyserHandler() const
diff --git a/third_party/WebKit/Source/modules/webaudio/AnalyserNode.h b/third_party/WebKit/Source/modules/webaudio/AnalyserNode.h
index 3611e50..a71d9c4 100644
--- a/third_party/WebKit/Source/modules/webaudio/AnalyserNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/AnalyserNode.h
@@ -68,7 +68,7 @@ private:
 class AnalyserNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static AnalyserNode* create(AudioContext*, float sampleRate);
+    static AnalyserNode* create(AudioContext&, float sampleRate);
 
     unsigned fftSize() const;
     void setFftSize(unsigned size, ExceptionState&);
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioBufferSourceNode.cpp b/third_party/WebKit/Source/modules/webaudio/AudioBufferSourceNode.cpp
index b09b015..505f3b8 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioBufferSourceNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioBufferSourceNode.cpp
@@ -567,14 +567,14 @@ DEFINE_TRACE(AudioBufferSourceHandler)
 // ----------------------------------------------------------------
 AudioBufferSourceNode::AudioBufferSourceNode(AudioContext& context, float sampleRate)
     : AudioScheduledSourceNode(context)
-    , m_playbackRate(AudioParam::create(&context, 1.0))
+    , m_playbackRate(AudioParam::create(context, 1.0))
 {
     setHandler(new AudioBufferSourceHandler(*this, sampleRate, m_playbackRate->handler()));
 }
 
-AudioBufferSourceNode* AudioBufferSourceNode::create(AudioContext* context, float sampleRate)
+AudioBufferSourceNode* AudioBufferSourceNode::create(AudioContext& context, float sampleRate)
 {
-    return new AudioBufferSourceNode(*context, sampleRate);
+    return new AudioBufferSourceNode(context, sampleRate);
 }
 
 DEFINE_TRACE(AudioBufferSourceNode)
@@ -635,7 +635,7 @@ void AudioBufferSourceNode::setLoopEnd(double loopEnd)
 
 void AudioBufferSourceNode::start(ExceptionState& exceptionState)
 {
-    audioBufferSourceHandler().start(exceptionState);
+    audioBufferSourceHandler().start(0, exceptionState);
 }
 
 void AudioBufferSourceNode::start(double when, ExceptionState& exceptionState)
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioBufferSourceNode.h b/third_party/WebKit/Source/modules/webaudio/AudioBufferSourceNode.h
index 0f0f5ad..2de43bf 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioBufferSourceNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/AudioBufferSourceNode.h
@@ -60,7 +60,6 @@ public:
     unsigned numberOfChannels();
 
     // Play-state
-    void start(ExceptionState& exceptionState) { start(0, exceptionState); }
     void start(double when, ExceptionState&);
     void start(double when, double grainOffset, ExceptionState&);
     void start(double when, double grainOffset, double grainDuration, ExceptionState&);
@@ -150,7 +149,7 @@ private:
 class AudioBufferSourceNode final : public AudioScheduledSourceNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static AudioBufferSourceNode* create(AudioContext*, float sampleRate);
+    static AudioBufferSourceNode* create(AudioContext&, float sampleRate);
     DECLARE_VIRTUAL_TRACE();
     AudioBufferSourceHandler& audioBufferSourceHandler() const;
 
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/AudioContext.cpp
index 2c133d9..61e50f6 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioContext.cpp
@@ -294,7 +294,7 @@ AudioBufferSourceNode* AudioContext::createBufferSource(ExceptionState& exceptio
         return nullptr;
     }
 
-    AudioBufferSourceNode* node = AudioBufferSourceNode::create(this, sampleRate());
+    AudioBufferSourceNode* node = AudioBufferSourceNode::create(*this, sampleRate());
 
     // Do not add a reference to this source node now. The reference will be added when start() is
     // called.
@@ -326,7 +326,7 @@ MediaElementAudioSourceNode* AudioContext::createMediaElementSource(HTMLMediaEle
         return nullptr;
     }
 
-    MediaElementAudioSourceNode* node = MediaElementAudioSourceNode::create(this, mediaElement);
+    MediaElementAudioSourceNode* node = MediaElementAudioSourceNode::create(*this, *mediaElement);
 
     mediaElement->setAudioSourceNode(&node->mediaElementAudioSourceHandler());
 
@@ -361,7 +361,7 @@ MediaStreamAudioSourceNode* AudioContext::createMediaStreamSource(MediaStream* m
     // Use the first audio track in the media stream.
     MediaStreamTrack* audioTrack = audioTracks[0];
     OwnPtr<AudioSourceProvider> provider = audioTrack->createWebAudioSource();
-    MediaStreamAudioSourceNode* node = MediaStreamAudioSourceNode::create(this, mediaStream, audioTrack, provider.release());
+    MediaStreamAudioSourceNode* node = MediaStreamAudioSourceNode::create(*this, *mediaStream, audioTrack, provider.release());
 
     // FIXME: Only stereo streams are supported right now. We should be able to accept multi-channel streams.
     node->mediaStreamAudioSourceHandler().setFormat(2, sampleRate());
@@ -378,38 +378,23 @@ MediaStreamAudioDestinationNode* AudioContext::createMediaStreamDestination(Exce
     }
 
     // Set number of output channels to stereo by default.
-    return MediaStreamAudioDestinationNode::create(this, 2);
+    return MediaStreamAudioDestinationNode::create(*this, 2);
 }
 
 ScriptProcessorNode* AudioContext::createScriptProcessor(ExceptionState& exceptionState)
 {
-    if (isContextClosed()) {
-        throwExceptionForClosedState(exceptionState);
-        return nullptr;
-    }
-
     // Set number of input/output channels to stereo by default.
     return createScriptProcessor(0, 2, 2, exceptionState);
 }
 
 ScriptProcessorNode* AudioContext::createScriptProcessor(size_t bufferSize, ExceptionState& exceptionState)
 {
-    if (isContextClosed()) {
-        throwExceptionForClosedState(exceptionState);
-        return nullptr;
-    }
-
     // Set number of input/output channels to stereo by default.
     return createScriptProcessor(bufferSize, 2, 2, exceptionState);
 }
 
 ScriptProcessorNode* AudioContext::createScriptProcessor(size_t bufferSize, size_t numberOfInputChannels, ExceptionState& exceptionState)
 {
-    if (isContextClosed()) {
-        throwExceptionForClosedState(exceptionState);
-        return nullptr;
-    }
-
     // Set number of output channels to stereo by default.
     return createScriptProcessor(bufferSize, numberOfInputChannels, 2, exceptionState);
 }
@@ -423,7 +408,7 @@ ScriptProcessorNode* AudioContext::createScriptProcessor(size_t bufferSize, size
         return nullptr;
     }
 
-    ScriptProcessorNode* node = ScriptProcessorNode::create(this, sampleRate(), bufferSize, numberOfInputChannels, numberOfOutputChannels);
+    ScriptProcessorNode* node = ScriptProcessorNode::create(*this, sampleRate(), bufferSize, numberOfInputChannels, numberOfOutputChannels);
 
     if (!node) {
         if (!numberOfInputChannels && !numberOfOutputChannels) {
@@ -463,7 +448,7 @@ StereoPannerNode* AudioContext::createStereoPanner(ExceptionState& exceptionStat
         return nullptr;
     }
 
-    return StereoPannerNode::create(this, sampleRate());
+    return StereoPannerNode::create(*this, sampleRate());
 }
 
 BiquadFilterNode* AudioContext::createBiquadFilter(ExceptionState& exceptionState)
@@ -474,7 +459,7 @@ BiquadFilterNode* AudioContext::createBiquadFilter(ExceptionState& exceptionStat
         return nullptr;
     }
 
-    return BiquadFilterNode::create(this, sampleRate());
+    return BiquadFilterNode::create(*this, sampleRate());
 }
 
 WaveShaperNode* AudioContext::createWaveShaper(ExceptionState& exceptionState)
@@ -485,7 +470,7 @@ WaveShaperNode* AudioContext::createWaveShaper(ExceptionState& exceptionState)
         return nullptr;
     }
 
-    return WaveShaperNode::create(this);
+    return WaveShaperNode::create(*this);
 }
 
 PannerNode* AudioContext::createPanner(ExceptionState& exceptionState)
@@ -496,7 +481,7 @@ PannerNode* AudioContext::createPanner(ExceptionState& exceptionState)
         return nullptr;
     }
 
-    return PannerNode::create(this, sampleRate());
+    return PannerNode::create(*this, sampleRate());
 }
 
 ConvolverNode* AudioContext::createConvolver(ExceptionState& exceptionState)
@@ -507,7 +492,7 @@ ConvolverNode* AudioContext::createConvolver(ExceptionState& exceptionState)
         return nullptr;
     }
 
-    return ConvolverNode::create(this, sampleRate());
+    return ConvolverNode::create(*this, sampleRate());
 }
 
 DynamicsCompressorNode* AudioContext::createDynamicsCompressor(ExceptionState& exceptionState)
@@ -518,7 +503,7 @@ DynamicsCompressorNode* AudioContext::createDynamicsCompressor(ExceptionState& e
         return nullptr;
     }
 
-    return DynamicsCompressorNode::create(this, sampleRate());
+    return DynamicsCompressorNode::create(*this, sampleRate());
 }
 
 AnalyserNode* AudioContext::createAnalyser(ExceptionState& exceptionState)
@@ -529,7 +514,7 @@ AnalyserNode* AudioContext::createAnalyser(ExceptionState& exceptionState)
         return nullptr;
     }
 
-    return AnalyserNode::create(this, sampleRate());
+    return AnalyserNode::create(*this, sampleRate());
 }
 
 GainNode* AudioContext::createGain(ExceptionState& exceptionState)
@@ -540,16 +525,11 @@ GainNode* AudioContext::createGain(ExceptionState& exceptionState)
         return nullptr;
     }
 
-    return GainNode::create(this, sampleRate());
+    return GainNode::create(*this, sampleRate());
 }
 
 DelayNode* AudioContext::createDelay(ExceptionState& exceptionState)
 {
-    if (isContextClosed()) {
-        throwExceptionForClosedState(exceptionState);
-        return nullptr;
-    }
-
     const double defaultMaxDelayTime = 1;
     return createDelay(defaultMaxDelayTime, exceptionState);
 }
@@ -562,19 +542,11 @@ DelayNode* AudioContext::createDelay(double maxDelayTime, ExceptionState& except
         return nullptr;
     }
 
-    DelayNode* node = DelayNode::create(this, sampleRate(), maxDelayTime, exceptionState);
-    if (exceptionState.hadException())
-        return nullptr;
-    return node;
+    return DelayNode::create(*this, sampleRate(), maxDelayTime, exceptionState);
 }
 
 ChannelSplitterNode* AudioContext::createChannelSplitter(ExceptionState& exceptionState)
 {
-    if (isContextClosed()) {
-        throwExceptionForClosedState(exceptionState);
-        return nullptr;
-    }
-
     const unsigned ChannelSplitterDefaultNumberOfOutputs = 6;
     return createChannelSplitter(ChannelSplitterDefaultNumberOfOutputs, exceptionState);
 }
@@ -588,7 +560,7 @@ ChannelSplitterNode* AudioContext::createChannelSplitter(size_t numberOfOutputs,
         return nullptr;
     }
 
-    ChannelSplitterNode* node = ChannelSplitterNode::create(this, sampleRate(), numberOfOutputs);
+    ChannelSplitterNode* node = ChannelSplitterNode::create(*this, sampleRate(), numberOfOutputs);
 
     if (!node) {
         exceptionState.throwDOMException(
@@ -604,11 +576,6 @@ ChannelSplitterNode* AudioContext::createChannelSplitter(size_t numberOfOutputs,
 
 ChannelMergerNode* AudioContext::createChannelMerger(ExceptionState& exceptionState)
 {
-    if (isContextClosed()) {
-        throwExceptionForClosedState(exceptionState);
-        return nullptr;
-    }
-
     const unsigned ChannelMergerDefaultNumberOfInputs = 6;
     return createChannelMerger(ChannelMergerDefaultNumberOfInputs, exceptionState);
 }
@@ -621,7 +588,7 @@ ChannelMergerNode* AudioContext::createChannelMerger(size_t numberOfInputs, Exce
         return nullptr;
     }
 
-    ChannelMergerNode* node = ChannelMergerNode::create(this, sampleRate(), numberOfInputs);
+    ChannelMergerNode* node = ChannelMergerNode::create(*this, sampleRate(), numberOfInputs);
 
     if (!node) {
         exceptionState.throwDOMException(
@@ -643,7 +610,7 @@ OscillatorNode* AudioContext::createOscillator(ExceptionState& exceptionState)
         return nullptr;
     }
 
-    OscillatorNode* node = OscillatorNode::create(this, sampleRate());
+    OscillatorNode* node = OscillatorNode::create(*this, sampleRate());
 
     // Do not add a reference to this source node now. The reference will be added when start() is
     // called.
@@ -1010,14 +977,6 @@ void AudioContext::unregisterLiveNode(AudioNode& node)
     m_liveNodes.remove(&node);
 }
 
-void DeferredTaskHandler::disposeOutputs(AudioHandler& node)
-{
-    ASSERT(isGraphOwner());
-    ASSERT(isMainThread());
-    for (unsigned i = 0; i < node.numberOfOutputs(); ++i)
-        node.output(i)->dispose();
-}
-
 void DeferredTaskHandler::markSummingJunctionDirty(AudioSummingJunction* summingJunction)
 {
     ASSERT(isGraphOwner());
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioContext.h b/third_party/WebKit/Source/modules/webaudio/AudioContext.h
index 7db4997..6e17e01 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioContext.h
+++ b/third_party/WebKit/Source/modules/webaudio/AudioContext.h
@@ -109,7 +109,6 @@ public:
 
     void markAudioNodeOutputDirty(AudioNodeOutput*);
     void removeMarkedAudioNodeOutput(AudioNodeOutput*);
-    void disposeOutputs(AudioHandler&);
 
     // In AudioNode::breakConnection() and deref(), a tryLock() is used for
     // calling actual processing, but if it fails keep track here.
@@ -174,13 +173,8 @@ private:
     HashSet<AudioHandler*> m_deferredCountModeChange;
 
     // These two HashSet must be accessed only when the graph lock is held.
-    // Oilpan: These HashSet should be HeapHashSet<WeakMember<AudioNodeOutput>>
-    // ideally. But it's difficult to lock them correctly during GC.
-    // Oilpan: Since items are added to these hash sets by the audio thread (not
-    // registered to Oilpan), we cannot use HeapHashSets.
-    GC_PLUGIN_IGNORE("http://crbug.com/404527")
+    // These raw pointers are safe because their destructors unregister them.
     HashSet<AudioSummingJunction*> m_dirtySummingJunctions;
-    GC_PLUGIN_IGNORE("http://crbug.com/404527")
     HashSet<AudioNodeOutput*> m_dirtyAudioNodeOutputs;
 
     // Only accessed in the audio thread.
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp b/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
index b123e6e..5b3c78e 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioNode.cpp
@@ -100,7 +100,8 @@ void AudioHandler::dispose()
 
     context()->handler().removeChangedChannelCountMode(this);
     context()->handler().removeAutomaticPullNode(this);
-    context()->handler().disposeOutputs(*this);
+    for (auto& output : m_outputs)
+        output->dispose();
 }
 
 String AudioHandler::nodeTypeName() const
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioParam.cpp b/third_party/WebKit/Source/modules/webaudio/AudioParam.cpp
index ffd14c9..f202e0c 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioParam.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioParam.cpp
@@ -194,15 +194,14 @@ void AudioParamHandler::disconnect(AudioNodeOutput& output)
 
 // ----------------------------------------------------------------
 
-AudioParam::AudioParam(AudioContext* context, double defaultValue)
+AudioParam::AudioParam(AudioContext& context, double defaultValue)
     : m_handler(AudioParamHandler::create(context, defaultValue))
     , m_context(context)
 {
 }
 
-AudioParam* AudioParam::create(AudioContext* context, double defaultValue)
+AudioParam* AudioParam::create(AudioContext& context, double defaultValue)
 {
-    ASSERT(context);
     return new AudioParam(context, defaultValue);
 }
 
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioParam.h b/third_party/WebKit/Source/modules/webaudio/AudioParam.h
index efd4e22..6052e1a 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioParam.h
+++ b/third_party/WebKit/Source/modules/webaudio/AudioParam.h
@@ -54,7 +54,7 @@ public:
     static const double DefaultSmoothingConstant;
     static const double SnapThreshold;
 
-    static PassRefPtr<AudioParamHandler> create(AudioContext* context, double defaultValue)
+    static PassRefPtr<AudioParamHandler> create(AudioContext& context, double defaultValue)
     {
         return adoptRef(new AudioParamHandler(context, defaultValue));
     }
@@ -100,12 +100,12 @@ public:
     void disconnect(AudioNodeOutput&);
 
 private:
-    AudioParamHandler(AudioContext* context, double defaultValue)
-        : AudioSummingJunction(context->handler())
+    AudioParamHandler(AudioContext& context, double defaultValue)
+        : AudioSummingJunction(context.handler())
         , m_value(defaultValue)
         , m_defaultValue(defaultValue)
         , m_smoothedValue(defaultValue)
-        , m_context(*context) { }
+        , m_context(context) { }
 
     // sampleAccurate corresponds to a-rate (audio rate) vs. k-rate in the Web Audio specification.
     void calculateFinalValues(float* values, unsigned numberOfValues, bool sampleAccurate);
@@ -128,7 +128,7 @@ private:
 class AudioParam final : public GarbageCollectedFinalized<AudioParam>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static AudioParam* create(AudioContext*, double defaultValue);
+    static AudioParam* create(AudioContext&, double defaultValue);
     DECLARE_TRACE();
     // |handler| always returns a valid object.
     AudioParamHandler& handler() const { return *m_handler; }
@@ -146,7 +146,7 @@ public:
     void cancelScheduledValues(double startTime, ExceptionState&);
 
 private:
-    AudioParam(AudioContext*, double defaultValue);
+    AudioParam(AudioContext&, double defaultValue);
 
     RefPtr<AudioParamHandler> m_handler;
     Member<AudioContext> m_context;
diff --git a/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp b/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp
index e9e3631..0957cf2 100644
--- a/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.cpp
@@ -28,14 +28,14 @@
 
 namespace blink {
 
-BiquadFilterNode::BiquadFilterNode(AudioContext* context, float sampleRate)
-    : AudioNode(*context)
+BiquadFilterNode::BiquadFilterNode(AudioContext& context, float sampleRate)
+    : AudioNode(context)
     , m_frequency(AudioParam::create(context, 350.0))
     , m_q(AudioParam::create(context, 1))
     , m_gain(AudioParam::create(context, 0.0))
     , m_detune(AudioParam::create(context, 0.0))
 {
-    setHandler(new AudioBasicProcessorHandler(AudioHandler::NodeTypeBiquadFilter, *this, sampleRate, adoptPtr(new BiquadProcessor(sampleRate, 1, m_frequency->handler(), m_q->handler(), m_gain->handler(), m_detune->handler(), false))));
+    setHandler(new AudioBasicProcessorHandler(AudioHandler::NodeTypeBiquadFilter, *this, sampleRate, adoptPtr(new BiquadProcessor(sampleRate, 1, m_frequency->handler(), m_q->handler(), m_gain->handler(), m_detune->handler()))));
 }
 
 DEFINE_TRACE(BiquadFilterNode)
diff --git a/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.h b/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.h
index b28dd33..172e003 100644
--- a/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/BiquadFilterNode.h
@@ -48,7 +48,7 @@ public:
         ALLPASS = 7
     };
 
-    static BiquadFilterNode* create(AudioContext* context, float sampleRate)
+    static BiquadFilterNode* create(AudioContext& context, float sampleRate)
     {
         return new BiquadFilterNode(context, sampleRate);
     }
@@ -67,7 +67,7 @@ public:
     void getFrequencyResponse(const DOMFloat32Array* frequencyHz, DOMFloat32Array* magResponse, DOMFloat32Array* phaseResponse);
 
 private:
-    BiquadFilterNode(AudioContext*, float sampleRate);
+    BiquadFilterNode(AudioContext&, float sampleRate);
 
     BiquadProcessor* biquadProcessor() const;
     bool setType(unsigned); // Returns true on success.
diff --git a/third_party/WebKit/Source/modules/webaudio/BiquadProcessor.cpp b/third_party/WebKit/Source/modules/webaudio/BiquadProcessor.cpp
index afa46c9..e67f9b5 100644
--- a/third_party/WebKit/Source/modules/webaudio/BiquadProcessor.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/BiquadProcessor.cpp
@@ -30,7 +30,7 @@
 
 namespace blink {
 
-BiquadProcessor::BiquadProcessor(float sampleRate, size_t numberOfChannels, AudioParamHandler& frequency, AudioParamHandler& q, AudioParamHandler& gain, AudioParamHandler& detune, bool autoInitialize)
+BiquadProcessor::BiquadProcessor(float sampleRate, size_t numberOfChannels, AudioParamHandler& frequency, AudioParamHandler& q, AudioParamHandler& gain, AudioParamHandler& detune)
     : AudioDSPKernelProcessor(sampleRate, numberOfChannels)
     , m_type(LowPass)
     , m_parameter1(frequency)
@@ -40,8 +40,6 @@ BiquadProcessor::BiquadProcessor(float sampleRate, size_t numberOfChannels, Audi
     , m_filterCoefficientsDirty(true)
     , m_hasSampleAccurateValues(false)
 {
-    if (autoInitialize)
-        initialize();
 }
 
 BiquadProcessor::~BiquadProcessor()
diff --git a/third_party/WebKit/Source/modules/webaudio/BiquadProcessor.h b/third_party/WebKit/Source/modules/webaudio/BiquadProcessor.h
index f333a3c..5255ffd 100644
--- a/third_party/WebKit/Source/modules/webaudio/BiquadProcessor.h
+++ b/third_party/WebKit/Source/modules/webaudio/BiquadProcessor.h
@@ -49,7 +49,7 @@ public:
         Allpass = 7
     };
 
-    BiquadProcessor(float sampleRate, size_t numberOfChannels, AudioParamHandler& frequency, AudioParamHandler& q, AudioParamHandler& gain, AudioParamHandler& detune, bool autoInitialize);
+    BiquadProcessor(float sampleRate, size_t numberOfChannels, AudioParamHandler& frequency, AudioParamHandler& q, AudioParamHandler& gain, AudioParamHandler& detune);
     virtual ~BiquadProcessor();
 
     virtual PassOwnPtr<AudioDSPKernel> createKernel() override;
diff --git a/third_party/WebKit/Source/modules/webaudio/ChannelMergerNode.cpp b/third_party/WebKit/Source/modules/webaudio/ChannelMergerNode.cpp
index f1f9e4e..ed14245 100644
--- a/third_party/WebKit/Source/modules/webaudio/ChannelMergerNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/ChannelMergerNode.cpp
@@ -130,11 +130,11 @@ ChannelMergerNode::ChannelMergerNode(AudioContext& context, float sampleRate, un
     setHandler(new ChannelMergerHandler(*this, sampleRate, numberOfInputs));
 }
 
-ChannelMergerNode* ChannelMergerNode::create(AudioContext* context, float sampleRate, unsigned numberOfInputs)
+ChannelMergerNode* ChannelMergerNode::create(AudioContext& context, float sampleRate, unsigned numberOfInputs)
 {
     if (!numberOfInputs || numberOfInputs > AudioContext::maxNumberOfChannels())
         return nullptr;
-    return new ChannelMergerNode(*context, sampleRate, numberOfInputs);
+    return new ChannelMergerNode(context, sampleRate, numberOfInputs);
 }
 
 } // namespace blink
diff --git a/third_party/WebKit/Source/modules/webaudio/ChannelMergerNode.h b/third_party/WebKit/Source/modules/webaudio/ChannelMergerNode.h
index e2edf67..0eddddf 100644
--- a/third_party/WebKit/Source/modules/webaudio/ChannelMergerNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/ChannelMergerNode.h
@@ -48,7 +48,7 @@ public:
 class ChannelMergerNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static ChannelMergerNode* create(AudioContext*, float sampleRate, unsigned numberOfInputs);
+    static ChannelMergerNode* create(AudioContext&, float sampleRate, unsigned numberOfInputs);
 
 private:
     ChannelMergerNode(AudioContext&, float sampleRate, unsigned numberOfInputs);
diff --git a/third_party/WebKit/Source/modules/webaudio/ChannelSplitterNode.cpp b/third_party/WebKit/Source/modules/webaudio/ChannelSplitterNode.cpp
index 93b00d4..df042c2 100644
--- a/third_party/WebKit/Source/modules/webaudio/ChannelSplitterNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/ChannelSplitterNode.cpp
@@ -75,11 +75,11 @@ ChannelSplitterNode::ChannelSplitterNode(AudioContext& context, float sampleRate
     setHandler(new ChannelSplitterHandler(*this, sampleRate, numberOfOutputs));
 }
 
-ChannelSplitterNode* ChannelSplitterNode::create(AudioContext* context, float sampleRate, unsigned numberOfOutputs)
+ChannelSplitterNode* ChannelSplitterNode::create(AudioContext& context, float sampleRate, unsigned numberOfOutputs)
 {
     if (!numberOfOutputs || numberOfOutputs > AudioContext::maxNumberOfChannels())
         return nullptr;
-    return new ChannelSplitterNode(*context, sampleRate, numberOfOutputs);
+    return new ChannelSplitterNode(context, sampleRate, numberOfOutputs);
 }
 
 } // namespace blink
diff --git a/third_party/WebKit/Source/modules/webaudio/ChannelSplitterNode.h b/third_party/WebKit/Source/modules/webaudio/ChannelSplitterNode.h
index e29a7a2d..41260fe 100644
--- a/third_party/WebKit/Source/modules/webaudio/ChannelSplitterNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/ChannelSplitterNode.h
@@ -43,7 +43,7 @@ public:
 class ChannelSplitterNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static ChannelSplitterNode* create(AudioContext*, float sampleRate, unsigned numberOfOutputs);
+    static ChannelSplitterNode* create(AudioContext&, float sampleRate, unsigned numberOfOutputs);
 
 private:
     ChannelSplitterNode(AudioContext&, float sampleRate, unsigned numberOfOutputs);
diff --git a/third_party/WebKit/Source/modules/webaudio/ConvolverNode.cpp b/third_party/WebKit/Source/modules/webaudio/ConvolverNode.cpp
index 4252e79..191436c 100644
--- a/third_party/WebKit/Source/modules/webaudio/ConvolverNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/ConvolverNode.cpp
@@ -195,9 +195,9 @@ ConvolverNode::ConvolverNode(AudioContext& context, float sampleRate)
     setHandler(new ConvolverHandler(*this, sampleRate));
 }
 
-ConvolverNode* ConvolverNode::create(AudioContext* context, float sampleRate)
+ConvolverNode* ConvolverNode::create(AudioContext& context, float sampleRate)
 {
-    return new ConvolverNode(*context, sampleRate);
+    return new ConvolverNode(context, sampleRate);
 }
 
 ConvolverHandler& ConvolverNode::convolverHandler() const
diff --git a/third_party/WebKit/Source/modules/webaudio/ConvolverNode.h b/third_party/WebKit/Source/modules/webaudio/ConvolverNode.h
index f9d97de..64d4801 100644
--- a/third_party/WebKit/Source/modules/webaudio/ConvolverNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/ConvolverNode.h
@@ -73,7 +73,7 @@ private:
 class ConvolverNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static ConvolverNode* create(AudioContext*, float sampleRate);
+    static ConvolverNode* create(AudioContext&, float sampleRate);
 
     AudioBuffer* buffer() const;
     void setBuffer(AudioBuffer*, ExceptionState&);
diff --git a/third_party/WebKit/Source/modules/webaudio/DelayNode.cpp b/third_party/WebKit/Source/modules/webaudio/DelayNode.cpp
index 6958ff0..9a423b1 100644
--- a/third_party/WebKit/Source/modules/webaudio/DelayNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/DelayNode.cpp
@@ -35,14 +35,14 @@ namespace blink {
 
 const double maximumAllowedDelayTime = 180;
 
-DelayNode::DelayNode(AudioContext* context, float sampleRate, double maxDelayTime)
-    : AudioNode(*context)
+DelayNode::DelayNode(AudioContext& context, float sampleRate, double maxDelayTime)
+    : AudioNode(context)
     , m_delayTime(AudioParam::create(context, 0.0))
 {
     setHandler(new AudioBasicProcessorHandler(AudioHandler::NodeTypeDelay, *this, sampleRate, adoptPtr(new DelayProcessor(sampleRate, 1, m_delayTime->handler(), maxDelayTime))));
 }
 
-DelayNode* DelayNode::create(AudioContext* context, float sampleRate, double maxDelayTime, ExceptionState& exceptionState)
+DelayNode* DelayNode::create(AudioContext& context, float sampleRate, double maxDelayTime, ExceptionState& exceptionState)
 {
     if (maxDelayTime <= 0 || maxDelayTime >= maximumAllowedDelayTime) {
         exceptionState.throwDOMException(
diff --git a/third_party/WebKit/Source/modules/webaudio/DelayNode.h b/third_party/WebKit/Source/modules/webaudio/DelayNode.h
index d64f998..494dea7 100644
--- a/third_party/WebKit/Source/modules/webaudio/DelayNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/DelayNode.h
@@ -36,12 +36,12 @@ class ExceptionState;
 class DelayNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static DelayNode* create(AudioContext*, float sampleRate, double maxDelayTime, ExceptionState&);
+    static DelayNode* create(AudioContext&, float sampleRate, double maxDelayTime, ExceptionState&);
     DECLARE_VIRTUAL_TRACE();
     AudioParam* delayTime();
 
 private:
-    DelayNode(AudioContext*, float sampleRate, double maxDelayTime);
+    DelayNode(AudioContext&, float sampleRate, double maxDelayTime);
 
     Member<AudioParam> m_delayTime;
 };
diff --git a/third_party/WebKit/Source/modules/webaudio/DynamicsCompressorNode.cpp b/third_party/WebKit/Source/modules/webaudio/DynamicsCompressorNode.cpp
index 8fe6fdc..98ade09 100644
--- a/third_party/WebKit/Source/modules/webaudio/DynamicsCompressorNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/DynamicsCompressorNode.cpp
@@ -125,19 +125,19 @@ double DynamicsCompressorHandler::latencyTime() const
 
 DynamicsCompressorNode::DynamicsCompressorNode(AudioContext& context, float sampleRate)
     : AudioNode(context)
-    , m_threshold(AudioParam::create(&context, -24))
-    , m_knee(AudioParam::create(&context, 30))
-    , m_ratio(AudioParam::create(&context, 12))
-    , m_reduction(AudioParam::create(&context, 0))
-    , m_attack(AudioParam::create(&context, 0.003))
-    , m_release(AudioParam::create(&context, 0.250))
+    , m_threshold(AudioParam::create(context, -24))
+    , m_knee(AudioParam::create(context, 30))
+    , m_ratio(AudioParam::create(context, 12))
+    , m_reduction(AudioParam::create(context, 0))
+    , m_attack(AudioParam::create(context, 0.003))
+    , m_release(AudioParam::create(context, 0.250))
 {
     setHandler(new DynamicsCompressorHandler(*this, sampleRate, m_threshold->handler(), m_knee->handler(), m_ratio->handler(), m_reduction->handler(), m_attack->handler(), m_release->handler()));
 }
 
-DynamicsCompressorNode* DynamicsCompressorNode::create(AudioContext* context, float sampleRate)
+DynamicsCompressorNode* DynamicsCompressorNode::create(AudioContext& context, float sampleRate)
 {
-    return new DynamicsCompressorNode(*context, sampleRate);
+    return new DynamicsCompressorNode(context, sampleRate);
 }
 
 DEFINE_TRACE(DynamicsCompressorNode)
diff --git a/third_party/WebKit/Source/modules/webaudio/DynamicsCompressorNode.h b/third_party/WebKit/Source/modules/webaudio/DynamicsCompressorNode.h
index 6701cd8..ea7c707 100644
--- a/third_party/WebKit/Source/modules/webaudio/DynamicsCompressorNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/DynamicsCompressorNode.h
@@ -61,7 +61,7 @@ private:
 class DynamicsCompressorNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static DynamicsCompressorNode* create(AudioContext*, float sampleRate);
+    static DynamicsCompressorNode* create(AudioContext&, float sampleRate);
     DECLARE_VIRTUAL_TRACE();
 
     AudioParam* threshold() const;
diff --git a/third_party/WebKit/Source/modules/webaudio/GainNode.cpp b/third_party/WebKit/Source/modules/webaudio/GainNode.cpp
index d0f4fe1..1b046e6 100644
--- a/third_party/WebKit/Source/modules/webaudio/GainNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/GainNode.cpp
@@ -108,14 +108,14 @@ void GainHandler::checkNumberOfChannelsForInput(AudioNodeInput* input)
 
 GainNode::GainNode(AudioContext& context, float sampleRate)
     : AudioNode(context)
-    , m_gain(AudioParam::create(&context, 1.0))
+    , m_gain(AudioParam::create(context, 1.0))
 {
     setHandler(new GainHandler(*this, sampleRate, m_gain->handler()));
 }
 
-GainNode* GainNode::create(AudioContext* context, float sampleRate)
+GainNode* GainNode::create(AudioContext& context, float sampleRate)
 {
-    return new GainNode(*context, sampleRate);
+    return new GainNode(context, sampleRate);
 }
 
 AudioParam* GainNode::gain() const
diff --git a/third_party/WebKit/Source/modules/webaudio/GainNode.h b/third_party/WebKit/Source/modules/webaudio/GainNode.h
index db783f8..e03d19e 100644
--- a/third_party/WebKit/Source/modules/webaudio/GainNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/GainNode.h
@@ -57,7 +57,7 @@ private:
 class GainNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static GainNode* create(AudioContext*, float sampleRate);
+    static GainNode* create(AudioContext&, float sampleRate);
     DECLARE_VIRTUAL_TRACE();
 
     AudioParam* gain() const;
diff --git a/third_party/WebKit/Source/modules/webaudio/MediaElementAudioSourceNode.cpp b/third_party/WebKit/Source/modules/webaudio/MediaElementAudioSourceNode.cpp
index ecf6d24..cd83fa5 100644
--- a/third_party/WebKit/Source/modules/webaudio/MediaElementAudioSourceNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/MediaElementAudioSourceNode.cpp
@@ -37,7 +37,7 @@
 
 namespace blink {
 
-MediaElementAudioSourceHandler::MediaElementAudioSourceHandler(AudioNode& node, HTMLMediaElement* mediaElement)
+MediaElementAudioSourceHandler::MediaElementAudioSourceHandler(AudioNode& node, HTMLMediaElement& mediaElement)
     : AudioHandler(NodeTypeMediaElementAudioSource, node, node.context()->sampleRate())
     , m_mediaElement(mediaElement)
     , m_sourceNumberOfChannels(0)
@@ -164,15 +164,15 @@ DEFINE_TRACE(MediaElementAudioSourceHandler)
 
 // ----------------------------------------------------------------
 
-MediaElementAudioSourceNode::MediaElementAudioSourceNode(AudioContext& context, HTMLMediaElement* mediaElement)
+MediaElementAudioSourceNode::MediaElementAudioSourceNode(AudioContext& context, HTMLMediaElement& mediaElement)
     : AudioSourceNode(context)
 {
     setHandler(new MediaElementAudioSourceHandler(*this, mediaElement));
 }
 
-MediaElementAudioSourceNode* MediaElementAudioSourceNode::create(AudioContext* context, HTMLMediaElement* mediaElement)
+MediaElementAudioSourceNode* MediaElementAudioSourceNode::create(AudioContext& context, HTMLMediaElement& mediaElement)
 {
-    return new MediaElementAudioSourceNode(*context, mediaElement);
+    return new MediaElementAudioSourceNode(context, mediaElement);
 }
 
 MediaElementAudioSourceHandler& MediaElementAudioSourceNode::mediaElementAudioSourceHandler() const
diff --git a/third_party/WebKit/Source/modules/webaudio/MediaElementAudioSourceNode.h b/third_party/WebKit/Source/modules/webaudio/MediaElementAudioSourceNode.h
index db1919c..fa5204d 100644
--- a/third_party/WebKit/Source/modules/webaudio/MediaElementAudioSourceNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/MediaElementAudioSourceNode.h
@@ -42,7 +42,7 @@ class HTMLMediaElement;
 class MediaElementAudioSourceHandler final : public AudioHandler, public AudioSourceProviderClient {
     USING_GARBAGE_COLLECTED_MIXIN(MediaElementAudioSourceHandler);
 public:
-    MediaElementAudioSourceHandler(AudioNode&, HTMLMediaElement*);
+    MediaElementAudioSourceHandler(AudioNode&, HTMLMediaElement&);
     virtual ~MediaElementAudioSourceHandler();
 
     HTMLMediaElement* mediaElement() { return m_mediaElement.get(); }
@@ -77,13 +77,13 @@ private:
 class MediaElementAudioSourceNode final : public AudioSourceNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static MediaElementAudioSourceNode* create(AudioContext*, HTMLMediaElement*);
+    static MediaElementAudioSourceNode* create(AudioContext&, HTMLMediaElement&);
     MediaElementAudioSourceHandler& mediaElementAudioSourceHandler() const;
 
     HTMLMediaElement* mediaElement() const;
 
 private:
-    MediaElementAudioSourceNode(AudioContext&, HTMLMediaElement*);
+    MediaElementAudioSourceNode(AudioContext&, HTMLMediaElement&);
 };
 
 } // namespace blink
diff --git a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.cpp b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.cpp
index 9548fee..dc41ab2 100644
--- a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.cpp
@@ -82,9 +82,9 @@ MediaStreamAudioDestinationNode::MediaStreamAudioDestinationNode(AudioContext& c
     setHandler(new MediaStreamAudioDestinationHandler(*this, numberOfChannels));
 }
 
-MediaStreamAudioDestinationNode* MediaStreamAudioDestinationNode::create(AudioContext* context, size_t numberOfChannels)
+MediaStreamAudioDestinationNode* MediaStreamAudioDestinationNode::create(AudioContext& context, size_t numberOfChannels)
 {
-    return new MediaStreamAudioDestinationNode(*context, numberOfChannels);
+    return new MediaStreamAudioDestinationNode(context, numberOfChannels);
 }
 
 MediaStream* MediaStreamAudioDestinationNode::stream() const
diff --git a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.h b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.h
index 38f6901..6181142 100644
--- a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioDestinationNode.h
@@ -61,7 +61,7 @@ private:
 class MediaStreamAudioDestinationNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static MediaStreamAudioDestinationNode* create(AudioContext*, size_t numberOfChannels);
+    static MediaStreamAudioDestinationNode* create(AudioContext&, size_t numberOfChannels);
     MediaStream* stream() const;
 
 private:
diff --git a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
index 5454237..8cf5fac 100644
--- a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
@@ -33,7 +33,7 @@
 
 namespace blink {
 
-MediaStreamAudioSourceHandler::MediaStreamAudioSourceHandler(AudioNode& node, MediaStream* mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
+MediaStreamAudioSourceHandler::MediaStreamAudioSourceHandler(AudioNode& node, MediaStream& mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
     : AudioHandler(NodeTypeMediaStreamAudioSource, node, node.context()->sampleRate())
     , m_mediaStream(mediaStream)
     , m_audioTrack(audioTrack)
@@ -120,15 +120,15 @@ DEFINE_TRACE(MediaStreamAudioSourceHandler)
 
 // ----------------------------------------------------------------
 
-MediaStreamAudioSourceNode::MediaStreamAudioSourceNode(AudioContext& context, MediaStream* mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
+MediaStreamAudioSourceNode::MediaStreamAudioSourceNode(AudioContext& context, MediaStream& mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
     : AudioSourceNode(context)
 {
     setHandler(new MediaStreamAudioSourceHandler(*this, mediaStream, audioTrack, audioSourceProvider));
 }
 
-MediaStreamAudioSourceNode* MediaStreamAudioSourceNode::create(AudioContext* context, MediaStream* mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
+MediaStreamAudioSourceNode* MediaStreamAudioSourceNode::create(AudioContext& context, MediaStream& mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
 {
-    return new MediaStreamAudioSourceNode(*context, mediaStream, audioTrack, audioSourceProvider);
+    return new MediaStreamAudioSourceNode(context, mediaStream, audioTrack, audioSourceProvider);
 }
 
 MediaStreamAudioSourceHandler& MediaStreamAudioSourceNode::mediaStreamAudioSourceHandler() const
diff --git a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.h b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.h
index 4264451..b385afe 100644
--- a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.h
@@ -42,7 +42,7 @@ class AudioContext;
 class MediaStreamAudioSourceHandler final : public AudioHandler, public AudioSourceProviderClient {
     USING_GARBAGE_COLLECTED_MIXIN(MediaStreamAudioSourceHandler);
 public:
-    MediaStreamAudioSourceHandler(AudioNode&, MediaStream*, MediaStreamTrack*, PassOwnPtr<AudioSourceProvider>);
+    MediaStreamAudioSourceHandler(AudioNode&, MediaStream&, MediaStreamTrack*, PassOwnPtr<AudioSourceProvider>);
     virtual ~MediaStreamAudioSourceHandler();
 
     MediaStream* mediaStream() { return m_mediaStream.get(); }
@@ -74,13 +74,13 @@ private:
 class MediaStreamAudioSourceNode final : public AudioSourceNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static MediaStreamAudioSourceNode* create(AudioContext*, MediaStream*, MediaStreamTrack*, PassOwnPtr<AudioSourceProvider>);
+    static MediaStreamAudioSourceNode* create(AudioContext&, MediaStream&, MediaStreamTrack*, PassOwnPtr<AudioSourceProvider>);
     MediaStreamAudioSourceHandler& mediaStreamAudioSourceHandler() const;
 
     MediaStream* mediaStream() const;
 
 private:
-    MediaStreamAudioSourceNode(AudioContext&, MediaStream*, MediaStreamTrack*, PassOwnPtr<AudioSourceProvider>);
+    MediaStreamAudioSourceNode(AudioContext&, MediaStream&, MediaStreamTrack*, PassOwnPtr<AudioSourceProvider>);
 };
 
 } // namespace blink
diff --git a/third_party/WebKit/Source/modules/webaudio/OscillatorNode.cpp b/third_party/WebKit/Source/modules/webaudio/OscillatorNode.cpp
index c16ecf6..8074db7 100644
--- a/third_party/WebKit/Source/modules/webaudio/OscillatorNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/OscillatorNode.cpp
@@ -343,16 +343,16 @@ DEFINE_TRACE(OscillatorHandler)
 OscillatorNode::OscillatorNode(AudioContext& context, float sampleRate)
     : AudioScheduledSourceNode(context)
     // Use musical pitch standard A440 as a default.
-    , m_frequency(AudioParam::create(&context, 440))
+    , m_frequency(AudioParam::create(context, 440))
     // Default to no detuning.
-    , m_detune(AudioParam::create(&context, 0))
+    , m_detune(AudioParam::create(context, 0))
 {
     setHandler(new OscillatorHandler(*this, sampleRate, m_frequency->handler(), m_detune->handler()));
 }
 
-OscillatorNode* OscillatorNode::create(AudioContext* context, float sampleRate)
+OscillatorNode* OscillatorNode::create(AudioContext& context, float sampleRate)
 {
-    return new OscillatorNode(*context, sampleRate);
+    return new OscillatorNode(context, sampleRate);
 }
 
 DEFINE_TRACE(OscillatorNode)
diff --git a/third_party/WebKit/Source/modules/webaudio/OscillatorNode.h b/third_party/WebKit/Source/modules/webaudio/OscillatorNode.h
index 9e0bf91..8dcd5af 100644
--- a/third_party/WebKit/Source/modules/webaudio/OscillatorNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/OscillatorNode.h
@@ -102,7 +102,7 @@ private:
 class OscillatorNode final : public AudioScheduledSourceNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static OscillatorNode* create(AudioContext*, float sampleRate);
+    static OscillatorNode* create(AudioContext&, float sampleRate);
     DECLARE_VIRTUAL_TRACE();
 
     String type() const;
diff --git a/third_party/WebKit/Source/modules/webaudio/PannerNode.cpp b/third_party/WebKit/Source/modules/webaudio/PannerNode.cpp
index 36ad422..e2cd990 100644
--- a/third_party/WebKit/Source/modules/webaudio/PannerNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/PannerNode.cpp
@@ -589,9 +589,9 @@ PannerNode::PannerNode(AudioContext& context, float sampelRate)
     setHandler(new PannerHandler(*this, sampelRate));
 }
 
-PannerNode* PannerNode::create(AudioContext* context, float sampleRate)
+PannerNode* PannerNode::create(AudioContext& context, float sampleRate)
 {
-    return new PannerNode(*context, sampleRate);
+    return new PannerNode(context, sampleRate);
 }
 
 PannerHandler& PannerNode::pannerHandler() const
diff --git a/third_party/WebKit/Source/modules/webaudio/PannerNode.h b/third_party/WebKit/Source/modules/webaudio/PannerNode.h
index b1eff63..7028e44 100644
--- a/third_party/WebKit/Source/modules/webaudio/PannerNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/PannerNode.h
@@ -153,7 +153,7 @@ private:
 class PannerNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static PannerNode* create(AudioContext*, float sampleRate);
+    static PannerNode* create(AudioContext&, float sampleRate);
     PannerHandler& pannerHandler() const;
 
     String panningModel() const;
diff --git a/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp b/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp
index 00240dd..2e42e1f 100644
--- a/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.cpp
@@ -281,7 +281,7 @@ static size_t chooseBufferSize()
     return bufferSize;
 }
 
-ScriptProcessorNode* ScriptProcessorNode::create(AudioContext* context, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels)
+ScriptProcessorNode* ScriptProcessorNode::create(AudioContext& context, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels)
 {
     // Check for valid buffer size.
     switch (bufferSize) {
@@ -309,7 +309,7 @@ ScriptProcessorNode* ScriptProcessorNode::create(AudioContext* context, float sa
     if (numberOfOutputChannels > AudioContext::maxNumberOfChannels())
         return nullptr;
 
-    return new ScriptProcessorNode(*context, sampleRate, bufferSize, numberOfInputChannels, numberOfOutputChannels);
+    return new ScriptProcessorNode(context, sampleRate, bufferSize, numberOfInputChannels, numberOfOutputChannels);
 }
 
 size_t ScriptProcessorNode::bufferSize() const
diff --git a/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.h b/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.h
index 25f00cf..95fabf2 100644
--- a/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/ScriptProcessorNode.h
@@ -97,7 +97,7 @@ public:
     // latency. Higher numbers will be necessary to avoid audio breakup and
     // glitches.
     // The value chosen must carefully balance between latency and audio quality.
-    static ScriptProcessorNode* create(AudioContext*, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels);
+    static ScriptProcessorNode* create(AudioContext&, float sampleRate, size_t bufferSize, unsigned numberOfInputChannels, unsigned numberOfOutputChannels);
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(audioprocess);
     size_t bufferSize() const;
diff --git a/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.cpp b/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.cpp
index 21e16fe..d3a1419 100644
--- a/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.cpp
@@ -153,14 +153,14 @@ void StereoPannerHandler::setChannelCountMode(const String& mode, ExceptionState
 
 StereoPannerNode::StereoPannerNode(AudioContext& context, float sampleRate)
     : AudioNode(context)
-    , m_pan(AudioParam::create(&context, 0))
+    , m_pan(AudioParam::create(context, 0))
 {
     setHandler(new StereoPannerHandler(*this, sampleRate, m_pan->handler()));
 }
 
-StereoPannerNode* StereoPannerNode::create(AudioContext* context, float sampleRate)
+StereoPannerNode* StereoPannerNode::create(AudioContext& context, float sampleRate)
 {
-    return new StereoPannerNode(*context, sampleRate);
+    return new StereoPannerNode(context, sampleRate);
 }
 
 DEFINE_TRACE(StereoPannerNode)
diff --git a/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.h b/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.h
index 4f4bc48..b78d70e 100644
--- a/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/StereoPannerNode.h
@@ -37,7 +37,7 @@ private:
 class StereoPannerNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static StereoPannerNode* create(AudioContext*, float sampleRate);
+    static StereoPannerNode* create(AudioContext&, float sampleRate);
     DECLARE_VIRTUAL_TRACE();
 
     AudioParam* pan() const;
diff --git a/third_party/WebKit/Source/modules/webaudio/WaveShaperNode.cpp b/third_party/WebKit/Source/modules/webaudio/WaveShaperNode.cpp
index bc3c734..3c3446a 100644
--- a/third_party/WebKit/Source/modules/webaudio/WaveShaperNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/WaveShaperNode.cpp
@@ -33,10 +33,10 @@
 
 namespace blink {
 
-WaveShaperNode::WaveShaperNode(AudioContext* context)
-    : AudioNode(*context)
+WaveShaperNode::WaveShaperNode(AudioContext& context)
+    : AudioNode(context)
 {
-    setHandler(new AudioBasicProcessorHandler(AudioHandler::NodeTypeWaveShaper, *this, context->sampleRate(), adoptPtr(new WaveShaperProcessor(context->sampleRate(), 1))));
+    setHandler(new AudioBasicProcessorHandler(AudioHandler::NodeTypeWaveShaper, *this, context.sampleRate(), adoptPtr(new WaveShaperProcessor(context.sampleRate(), 1))));
 
     handler().initialize();
 }
diff --git a/third_party/WebKit/Source/modules/webaudio/WaveShaperNode.h b/third_party/WebKit/Source/modules/webaudio/WaveShaperNode.h
index ffc989b..28ffc31 100644
--- a/third_party/WebKit/Source/modules/webaudio/WaveShaperNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/WaveShaperNode.h
@@ -37,7 +37,7 @@ class ExceptionState;
 class WaveShaperNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static WaveShaperNode* create(AudioContext* context)
+    static WaveShaperNode* create(AudioContext& context)
     {
         return new WaveShaperNode(context);
     }
@@ -50,7 +50,7 @@ public:
     String oversample() const;
 
 private:
-    explicit WaveShaperNode(AudioContext*);
+    explicit WaveShaperNode(AudioContext&);
 
     WaveShaperProcessor* waveShaperProcessor() const;
 };