AudioContext.decodeAudioData returns a Promise

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 d74b0cc089ea10bb9a9d6be7ac64e4a567f0d455..477c216bc1e7275ee8c2ea815deff84a83127737 100644
--- a/Source/modules/webaudio/AudioContext.h
+++ b/Source/modules/webaudio/AudioContext.h
@@ -124,7 +124,7 @@ public:
     AudioBuffer* createBuffer(unsigned numberOfChannels, size_t numberOfFrames, float sampleRate, ExceptionState&);
 
     // Asynchronous audio file data decoding.
-    void decodeAudioData(DOMArrayBuffer*, AudioBufferCallback*, AudioBufferCallback*, ExceptionState&);
+    ScriptPromise decodeAudioData(ScriptState*, DOMArrayBuffer*, AudioBufferCallback*, AudioBufferCallback*, ExceptionState&);
 
     AudioListener* listener() { return m_listener.get(); }
 
@@ -283,6 +283,7 @@ public:
     // Get the security origin for this audio context.
     SecurityOrigin* securityOrigin() const;
 
+    void removeAudioDecoderResolver(ScriptPromiseResolver*);
 protected:
     explicit AudioContext(Document*);
     AudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
@@ -417,6 +418,8 @@ private:
     void setContextState(AudioContextState);
 
     AsyncAudioDecoder m_audioDecoder;
+    // A vector of the ScriptPromiseResolvers the decodeAudioData method uses.
+    WillBeHeapVector<RefPtrWillBeMember<ScriptPromiseResolver>> m_audioDecoderResolvers;
 
     // Collection of nodes where the channel count mode has changed. We want the channel count mode
     // to change in the pre- or post-rendering phase so as not to disturb the running audio thread.
@@ -429,6 +432,11 @@ private:
     // Follows the destination's currentSampleFrame, but might be slightly behind due to locking.
     size_t m_cachedSampleFrame;
 
+    // When a context is closed, the sample rate is cleared.  But decodeAudioData can be called
+    // after the context has been closed and it needs the sample rate.  When the context is closed,
+    // the sample rate is saved here.
+    float m_closedContextSampleRate;
+
     // Tries to handle AudioBufferSourceNodes that were started but became disconnected or was never
     // connected. Because these never get pulled anymore, they will stay around forever. So if we
     // can, try to stop them so they can be collected.