Introduce KeepAliveWhilePending to ScriptPromiseResolverWithContext.

Source/modules/webmidi/NavigatorWebMIDI.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 15 matching lines @@
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef NavigatorWebMIDI_h
 #define NavigatorWebMIDI_h
 
 #include "bindings/v8/ScriptPromise.h"
 #include "core/frame/DOMWindowProperty.h"
+#include "modules/webmidi/MIDIAccessInitializer.h"
 #include "modules/webmidi/MIDIOptions.h"
 #include "platform/Supplementable.h"
 #include "platform/heap/Handle.h"
+#include "wtf/HashSet.h"
 
 namespace WebCore {
 
 class Navigator;
+class MIDIAccess;
 
-class NavigatorWebMIDI FINAL : public NoBaseWillBeGarbageCollectedFinalized<NavigatorWebMIDI>, public WillBeHeapSupplement<Navigator>, public DOMWindowProperty {
+class NavigatorWebMIDI FINAL : public NoBaseWillBeGarbageCollectedFinalized<NavigatorWebMIDI>, public WillBeHeapSupplement<Navigator>, public DOMWindowProperty, MIDIAccessInitializer::Client {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(NavigatorWebMIDI);
 public:
     virtual ~NavigatorWebMIDI();
     static NavigatorWebMIDI& from(Navigator&);
 
     static ScriptPromise requestMIDIAccess(ScriptState*, Navigator&, const Dictionary&);
-    ScriptPromise requestMIDIAccess(ScriptState*, const Dictionary&);
+
+    // MIDIAccessInitializer::Client implementaion
+    virtual void didFinishMIDIAccessInitialization(MIDIAccessInitializer*) OVERRIDE;
+    virtual void didFailMIDIAccessInitialization(MIDIAccessInitializer*) OVERRIDE;
 
     virtual void trace(Visitor* visitor) OVERRIDE { WillBeHeapSupplement<Navigator>::trace(visitor); }
 
 private:
+    ScriptPromise requestMIDIAccessInternal(ScriptState*, Navigator&, const Dictionary&);
+
+    HashSet<OwnPtr<MIDIAccessInitializer> > m_initializers;

[haraken, 2014/06/13 14:23:31]

I'm sorry for asking design questions a lot of times, but let me ask one more
thing:

- It seems that MIDIAccessInitializer is kept alive as long as you want to keep
the Navigator object alive.

- Then why don't you just make the MIDIAccessInitializer hold a RefPtr to the
Navigator?

- I want to understand the lifetime of the MIDIAccessInitializer, the Navigator
and the Promise returned back to JS.

     NavigatorWebMIDI(LocalFrame*);
     static const char* supplementName();
 };
 
 } // namespace WebCore
 
 #endif // NavigatorWebMIDI_h