Split "Online" and "Offline" AudioContext processing

Source/modules/webaudio/BiquadFilterNode.h

Index: Source/modules/webaudio/BiquadFilterNode.h
diff --git a/Source/modules/webaudio/BiquadFilterNode.h b/Source/modules/webaudio/BiquadFilterNode.h
index dcdc54b8172c2ee790b389c0d619a5951e3e08ba..ad8ea74535d5a1cf26fc5d1b677bfdb332d9611d 100644
--- a/Source/modules/webaudio/BiquadFilterNode.h
+++ b/Source/modules/webaudio/BiquadFilterNode.h
@@ -31,6 +31,7 @@
 
 namespace blink {
 
+class AbstractAudioContext;
 class AudioParam;
 
 class BiquadFilterNode final : public AudioNode {
@@ -48,7 +49,7 @@ public:
         ALLPASS = 7
     };
 
-    static BiquadFilterNode* create(AudioContext& context, float sampleRate)
+    static BiquadFilterNode* create(AbstractAudioContext& context, float sampleRate)
     {
         return new BiquadFilterNode(context, sampleRate);
     }
@@ -67,7 +68,7 @@ public:
     void getFrequencyResponse(const DOMFloat32Array* frequencyHz, DOMFloat32Array* magResponse, DOMFloat32Array* phaseResponse);
 
 private:
-    BiquadFilterNode(AudioContext&, float sampleRate);
+    BiquadFilterNode(AbstractAudioContext&, float sampleRate);
 
     BiquadProcessor* biquadProcessor() const;
     bool setType(unsigned); // Returns true on success.