Split "Online" and "Offline" AudioContext processing

Source/modules/webaudio/StereoPannerNode.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef StereoPannerNode_h
 #define StereoPannerNode_h
 
 #include "modules/webaudio/AudioNode.h"
 #include "modules/webaudio/AudioParam.h"
 #include "platform/audio/AudioBus.h"
 #include "platform/audio/Spatializer.h"
 
 namespace blink {
 
+class AbstractAudioContext;
+
 // StereoPannerNode is an AudioNode with one input and one output. It is
 // specifically designed for equal-power stereo panning.
 class StereoPannerHandler final : public AudioHandler {
 public:
     static PassRefPtr<StereoPannerHandler> create(AudioNode&, float sampleRate, AudioParamHandler& pan);
     ~StereoPannerHandler() override;
 
     void process(size_t framesToProcess) override;
     void initialize() override;
 
     void setChannelCount(unsigned long, ExceptionState&) final;
     void setChannelCountMode(const String&, ExceptionState&) final;
 
 private:
     StereoPannerHandler(AudioNode&, float sampleRate, AudioParamHandler& pan);
 
     OwnPtr<Spatializer> m_stereoPanner;
     RefPtr<AudioParamHandler> m_pan;
 
     AudioFloatArray m_sampleAccuratePanValues;
 
     // TODO(tkent): Use FRIEND_TEST macro provided by gtest_prod.h
     friend class StereoPannerNodeTest_StereoPannerLifetime_Test;
 };
 
 class StereoPannerNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    static StereoPannerNode* create(AudioContext&, float sampleRate);
+    static StereoPannerNode* create(AbstractAudioContext&, float sampleRate);
     DECLARE_VIRTUAL_TRACE();
 
     AudioParam* pan() const;
 
 private:
-    StereoPannerNode(AudioContext&, float sampleRate);
+    StereoPannerNode(AbstractAudioContext&, float sampleRate);
 
     Member<AudioParam> m_pan;
 };
 
 } // namespace blink
 
 #endif // StereoPannerNode_h