Web MIDI: implement MIDIAccessPromise

Source/modules/webmidi/MIDIAccessPromise.h

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+
+#ifndef MIDIAccessPromise_h
+#define MIDIAccessPromise_h
+
+#include "bindings/v8/ScriptWrappable.h"
+#include "core/dom/ActiveDOMObject.h"
+#include "modules/webmidi/MIDIOptions.h"
+#include "wtf/OwnPtr.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefCounted.h"
+
+namespace WebCore {
+
+class DOMError;
+class MIDIAccess;
+class MIDIErrorCallback;
+class MIDISuccessCallback;
+class ScriptExecutionContext;
+
+struct MIDIOptions;
+
+class MIDIAccessPromise : public RefCounted<MIDIAccessPromise>, public ScriptWrappable, public ActiveDOMObject {
+public:
+    static PassRefPtr<MIDIAccessPromise> create(ScriptExecutionContext*, const Dictionary&);
+    virtual ~MIDIAccessPromise();
+
+    void then(PassRefPtr<MIDISuccessCallback>, PassRefPtr<MIDIErrorCallback>);
+
+    // ActiveDOMObject
+    virtual bool canSuspend() const OVERRIDE { return true; }

[Chris Rogers, 2013/06/07 04:27:25]

For ActiveDOMObject, I think you also need to implement     virtual bool
hasPendingActivity() const;

and return |true| until either fulfill() or reject() is called.  Until the async
status (success/error) is determined, this must stay alive.

You may want to verify this with haraken.

[Takashi Toyoshima, 2013/06/07 04:55:17]

I see.
I indirectly realize right hasPendingActivity() behavior by adding
setPendingActivity()/unsetPendingActivity() at proper places.

+
+    void fulfill();
+    void reject(DOMError*);
+
+private:
+    enum State {
+        Pending,
+        Accepted,
+        Rejected,
+        Invoked,
+    };
+
+    MIDIAccessPromise(ScriptExecutionContext*, const Dictionary&);
+
+    ScriptExecutionContext* m_context;

[Chris Rogers, 2013/06/07 04:27:25]

Since we inherit from ActiveDOMObject, I don't think it's necessary to keep
track of m_context, since scriptExecutionContext() is a method

So this member can be removed

[Takashi Toyoshima, 2013/06/07 04:55:17]

Thanks. I forget to remove this when I change this class to be ActiveDOMObject.
Done.

+    State m_state;
+    RefPtr<MIDISuccessCallback> m_successCallback;
+    RefPtr<MIDIErrorCallback> m_errorCallback;
+    OwnPtr<MIDIOptions> m_options;
+    RefPtr<DOMError> m_error;
+    RefPtr<MIDIAccess> m_access;
+};
+
+} // namespace WebCore
+
+#endif // MIDIAccessPromise_h