Split "Online" and "Offline" AudioContext processing

Source/modules/webaudio/OfflineAudioContext.h

 /*
  * Copyright (C) 2012, 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
@@ skipping 22 matching lines @@
 class ExceptionState;
 
 class MODULES_EXPORT OfflineAudioContext final : public AudioContext {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static OfflineAudioContext* create(ExecutionContext*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate, ExceptionState&);
 
     virtual ~OfflineAudioContext();
 
     ScriptPromise startOfflineRendering(ScriptState*);
+
+    virtual ScriptPromise closeContext(ScriptState*) override final;
+    virtual ScriptPromise suspendContext(ScriptState*) override final;
+    virtual ScriptPromise resumeContext(ScriptState*) override final;
+
+    virtual bool hasRealtimeConstraint() override final { return false; }
+
 private:
     OfflineAudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
 };
 
 } // namespace blink
 
 #endif // OfflineAudioContext_h