Oilpan: cancel MIDI permission request when prefinalizing

Source/modules/webmidi/MIDIAccessInitializer.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MIDIAccessInitializer_h
 #define MIDIAccessInitializer_h
 
 #include "bindings/core/v8/ScriptPromise.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "modules/webmidi/MIDIAccessor.h"
 #include "modules/webmidi/MIDIAccessorClient.h"
 #include "modules/webmidi/MIDIPort.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/Vector.h"
 
 namespace blink {
 
 class MIDIOptions;
 class ScriptState;
 
 class MIDIAccessInitializer : public ScriptPromiseResolver, public MIDIAccessorClient {
+#if ENABLE(OILPAN)
+    USING_PRE_FINALIZER(MIDIAccessInitializer, dispose);

[haraken, 2014/12/19 03:47:16]

Just to confirm: The reason we cannot use WeakMember (i.e., have MIDIController
hold WeakMember<MIDIAccessInitializer>) is that the weak processing does not run
when the MIDIController and the MIDIAccessInitializer die together, right?
MIDIController always needs to cancel the permission request when the
MIDIAccessInitializer dies (regardless of whether the MIDIController dies at the
same time or not). Thus we need to use a pre-finalizer. Am I understanding
correctly?

+#endif
 public:
     struct PortDescriptor {
         String id;
         String manufacturer;
         String name;
         MIDIPort::MIDIPortTypeCode type;
         String version;
         bool isActive;
 
         PortDescriptor(const String& id, const String& manufacturer, const String& name, MIDIPort::MIDIPortTypeCode type, const String& version, bool isActive)
@@ skipping 20 matching lines @@
     virtual void didAddOutputPort(const String& id, const String& manufacturer, const String& name, const String& version, bool isActive) override;
     virtual void didSetInputPortState(unsigned portIndex, bool isActive) override;
     virtual void didSetOutputPortState(unsigned portIndex, bool isActive) override;
     virtual void didStartSession(bool success, const String& error, const String& message) override;
     virtual void didReceiveMIDIData(unsigned portIndex, const unsigned char* data, size_t length, double timeStamp) override { }
 
     void resolveSysexPermission(bool allowed);
     SecurityOrigin* securityOrigin() const;
 
 private:
-    ScriptPromise start();
-
     MIDIAccessInitializer(ScriptState*, const MIDIOptions&);
 
     ExecutionContext* executionContext() const;
+    ScriptPromise start();
+    void dispose();
 
     OwnPtr<MIDIAccessor> m_accessor;
+    Vector<PortDescriptor> m_portDescriptors;
     bool m_requestSysex;
-    Vector<PortDescriptor> m_portDescriptors;
 };
 
 } // namespace blink
 
 
 #endif // MIDIAccessInitializer_h