Oilpan: merge MIDIAccessInitializer's prefinalizers.

Source/modules/webmidi/MIDIAccessInitializer.cpp

Index: Source/modules/webmidi/MIDIAccessInitializer.cpp
diff --git a/Source/modules/webmidi/MIDIAccessInitializer.cpp b/Source/modules/webmidi/MIDIAccessInitializer.cpp
index 36d4b00cfd07e27b9eaeafeb009bca442a3078a4..18fc1085ad6d6dae3576fd676a8db4a23c17ed02 100644
--- a/Source/modules/webmidi/MIDIAccessInitializer.cpp
+++ b/Source/modules/webmidi/MIDIAccessInitializer.cpp
@@ -22,6 +22,10 @@ MIDIAccessInitializer::MIDIAccessInitializer(ScriptState* scriptState, const MID
     , m_requestSysex(false)
 {
 #if ENABLE(OILPAN)
+    // A prefinalizer has already been registered (as a LifecycleObserver);
+    // remove it and register a combined one, as the infrastructure doesn't
+    // support multiple prefinalizers for an object.

[haraken, 2015/01/28 09:53:10]

Shall we add a FIXME?

[sof, 2015/01/28 09:56:42]

Can do that, what did you have in mind? i.e., multiple prefinalizer support or
avoid there being multiple prefinalizers for MIDIAccessInitializer in the first
place?

[haraken, 2015/01/28 10:01:36]

Avoid multiple prefinalizers and add an ASSERT about it :)

[sof, 2015/01/28 10:56:38]

Done.

+    ThreadState::current()->unregisterPreFinalizer(*this);

[kouhei (in TOK), 2015/01/28 09:58:04]

How about
ThreadState::current()->unregisterPreFinalizer(static_cast<LifecycleObserver&>(*this));

(void*)(LifecycleObserver*)this may be != (void*)this

[sof, 2015/01/28 10:56:38]

Done.

     ThreadState::current()->registerPreFinalizer(*this);
 #endif
     if (options.hasSysex())
@@ -42,6 +46,11 @@ void MIDIAccessInitializer::dispose()
     ASSERT(document);
     if (MIDIController* controller = MIDIController::from(document->frame()))
         controller->cancelSysexPermissionRequest(this);
+
+#if ENABLE(OILPAN)
+    // Delegate to LifecycleObserver's prefinalizer.
+    LifecycleObserver::dispose();
+#endif
 }
 
 ScriptPromise MIDIAccessInitializer::start()