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diff --git a/WebCore/webaudio/AudioNode.h b/WebCore/webaudio/AudioNode.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 AudioNode_h
+#define AudioNode_h
+
+#include <wtf/OwnPtr.h>
+#include <wtf/PassOwnPtr.h>
+#include <wtf/RefPtr.h>
+#include <wtf/Vector.h>
+
+#define DEBUG_AUDIONODE_REFERENCES 0
+
+namespace WebCore {
+
+class AudioContext;
+class AudioNodeInput;
+class AudioNodeOutput;
+
+// An AudioNode is the basic building block for handling audio within an AudioContext.
+// It may be an audio source, an intermediate processing module, or an audio destination.
+// Each AudioNode can have inputs and/or outputs. An AudioSourceNode has no inputs and a single output.
+// An AudioDestinationNode has one input and no outputs and represents the final destination to the audio hardware.
+// Most processing nodes such as filters will have one input and one output, although multiple inputs and outputs are possible.
+
+class AudioNode {
+public:
+    enum { ProcessingSizeInFrames = 128 };
+
+    AudioNode(AudioContext*, double sampleRate);
+    virtual ~AudioNode();
+
+    AudioContext* context() { return m_context.get(); }
+
+    enum NodeType {
+        NodeTypeUnknown,
+        NodeTypeDestination,
+        NodeTypeAudioBufferSource,
+        NodeTypeJavaScript,
+        NodeTypeLowPass2Filter,
+        NodeTypeHighPass2Filter,
+        NodeTypePanner,
+        NodeTypeConvolver,
+        NodeTypeDelay,
+        NodeTypeGain,
+        NodeTypeChannelSplitter,
+        NodeTypeChannelMerger,
+        NodeTypeAnalyser,
+        NodeTypeEnd
+    };
+
+    NodeType type() const { return m_type; }
+    void setType(NodeType);
+
+    // We handle our own ref-counting because of the threading issues and subtle nature of
+    // how AudioNodes can continue processing (playing one-shot sound) after there are no more
+    // JavaScript references to the object.
+    enum RefType { RefTypeNormal, RefTypeConnection, RefTypeDisabled };
+
+    // Can be called from main thread or context's audio thread.
+    void ref(RefType refType = RefTypeNormal);
+    void deref(RefType refType = RefTypeNormal);
+
+    // Can be called from main thread or context's audio thread.  It must be called while the context's graph lock is held.
+    void finishDeref(RefType refType);
+
+    // The AudioNodeInput(s) (if any) will already have their input data available when process() is called.
+    // Subclasses will take this input data and put the results in the AudioBus(s) of its AudioNodeOutput(s) (if any).
+    // Called from context's audio thread.
+    virtual void process(size_t framesToProcess) = 0;
+
+    // Resets DSP processing state (clears delay lines, filter memory, etc.)
+    // Called from context's audio thread.
+    virtual void reset() = 0;
+
+    // No significant resources should be allocated until initialize() is called.
+    // Processing may not occur until a node is initialized.
+    virtual void initialize() = 0;
+    virtual void uninitialize() = 0;
+
+    bool isInitialized() const { return m_isInitialized; }
+    void lazyInitialize();
+
+    unsigned numberOfInputs() const { return m_inputs.size(); }
+    unsigned numberOfOutputs() const { return m_outputs.size(); }
+
+    AudioNodeInput* input(unsigned);
+    AudioNodeOutput* output(unsigned);
+
+    // connect() / disconnect() return true on success.
+    // Called from main thread by corresponding JavaScript methods.
+    bool connect(AudioNode* destination, unsigned outputIndex = 0, unsigned inputIndex = 0);
+    bool disconnect(unsigned outputIndex = 0);
+
+    double sampleRate() const { return m_sampleRate; }
+
+    // processIfNecessary() is called by our output(s) when the rendering graph needs this AudioNode to process.
+    // This method ensures that the AudioNode will only process once per rendering time quantum even if it's called repeatedly.
+    // This handles the case of "fanout" where an output is connected to multiple AudioNode inputs.
+    // Called from context's audio thread.
+    void processIfNecessary(size_t framesToProcess);
+
+    // Called when a new connection has been made to one of our inputs or the connection number of channels has changed.
+    // This potentially gives us enough information to perform a lazy initialization or, if necessary, a re-initialization.
+    // Called from main thread.
+    virtual void checkNumberOfChannelsForInput(AudioNodeInput*) { }
+
+#if DEBUG_AUDIONODE_REFERENCES
+    static void printNodeCounts();
+#endif
+
+protected:
+    // Inputs and outputs must be created before the AudioNode is initialized.
+    void addInput(PassOwnPtr<AudioNodeInput>);
+    void addOutput(PassOwnPtr<AudioNodeOutput>);
+    
+    // Called by processIfNecessary() to cause all parts of the rendering graph connected to us to process.
+    // Each rendering quantum, the audio data for each of the AudioNode's inputs will be available after this method is called.
+    // Called from context's audio thread.
+    virtual void pullInputs(size_t framesToProcess);
+
+    bool m_isInitialized;
+
+private:
+    NodeType m_type;
+    RefPtr<AudioContext> m_context;
+    double m_sampleRate;
+    Vector<OwnPtr<AudioNodeInput> > m_inputs;
+    Vector<OwnPtr<AudioNodeOutput> > m_outputs;
+
+    double m_lastProcessingTime;
+
+    // Ref-counting
+    volatile int m_normalRefCount;
+    volatile int m_connectionRefCount;
+    volatile int m_disabledRefCount;
+    
+    bool m_isMarkedForDeletion;
+    bool m_isDisabled;
+    
+#if DEBUG_AUDIONODE_REFERENCES
+    static bool s_isNodeCountInitialized;
+    static int s_nodeCount[NodeTypeEnd];
+#endif
+};
+
+} // namespace WebCore
+
+#endif // AudioNode_h