Implement suspend() and resume() for OfflineAudioContext

Source/modules/webaudio/AudioContext.h

Index: Source/modules/webaudio/AudioContext.h
diff --git a/Source/modules/webaudio/AudioContext.h b/Source/modules/webaudio/AudioContext.h
index 092eece9ac5f427e7bf33a1913c3ae1f5dd9c4b4..eb12bf450fad7e8a0476f6b215b18262d8bb72ca 100644
--- a/Source/modules/webaudio/AudioContext.h
+++ b/Source/modules/webaudio/AudioContext.h
@@ -219,11 +219,9 @@ public:
     virtual const AtomicString& interfaceName() const override final;
     virtual ExecutionContext* executionContext() const override final;
 
-    DEFINE_ATTRIBUTE_EVENT_LISTENER(complete);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(statechange);
 
     void startRendering();
-    void fireCompletionEvent();
     void notifyStateChange();
 
     // A context is considered closed if:
@@ -238,11 +236,19 @@ public:
     // Get the security origin for this audio context.
     SecurityOrigin* securityOrigin() const;
 
+    // TODO: Refactoring needed. These are OfflineAudioContext-specific tasks.
+    virtual void fireCompletionEvent();
+    virtual bool shouldSuspendNow();
+    virtual void resolvePendingSuspendPromises();
+    AudioBuffer* renderTarget() const { return m_renderTarget.get(); }
+
 protected:
     explicit AudioContext(Document*);
     AudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
 
-    RefPtrWillBeMember<ScriptPromiseResolver> m_offlineResolver;
+    // Shared with OfflineAudioContext.
+    void setContextState(AudioContextState);
+
 private:
     void initialize();
     void uninitialize();
@@ -307,7 +313,6 @@ private:
 
     // The state of the AudioContext.
     AudioContextState m_contextState;
-    void setContextState(AudioContextState);
 
     AsyncAudioDecoder m_audioDecoder;
 
@@ -319,6 +324,9 @@ private:
     // can, try to stop them so they can be collected.
     void handleStoppableSourceNodes();
 
+    // Perform common tasks after the render quantum. Called by handlePostRenderTasks().
+    void performPostRenderTasks();
+
     // This is considering 32 is large enough for multiple channels audio.
     // It is somewhat arbitrary and could be increased if necessary.
     enum { MaxNumberOfChannels = 32 };