Oilpan: move mutation observers to the Oilpan heap.

Source/core/dom/MutationObserver.h

Index: Source/core/dom/MutationObserver.h
diff --git a/Source/core/dom/MutationObserver.h b/Source/core/dom/MutationObserver.h
index 086e600ea428368e05cd9bb3eb91009603317679..fad6e044da2994c440ddee1574861cd924adbd52 100644
--- a/Source/core/dom/MutationObserver.h
+++ b/Source/core/dom/MutationObserver.h
@@ -32,6 +32,7 @@
 #define MutationObserver_h
 
 #include "bindings/v8/ScriptWrappable.h"
+#include "platform/heap/Handle.h"
 #include "wtf/HashSet.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/PassRefPtr.h"
@@ -51,7 +52,7 @@ class Node;
 typedef unsigned char MutationObserverOptions;
 typedef unsigned char MutationRecordDeliveryOptions;
 
-class MutationObserver : public RefCounted<MutationObserver>, public ScriptWrappable {
+class MutationObserver FINAL : public RefCountedWillBeGarbageCollectedFinalized<MutationObserver>, public ScriptWrappable {
 public:
     enum MutationType {
         ChildList = 1 << 0,
@@ -71,23 +72,25 @@ public:
         CharacterDataOldValue = 1 << 6,
     };
 
-    static PassRefPtr<MutationObserver> create(PassOwnPtr<MutationCallback>);
+    static PassRefPtrWillBeRawPtr<MutationObserver> create(PassOwnPtr<MutationCallback>);
     static void resumeSuspendedObservers();
     static void deliverMutations();
 
     ~MutationObserver();
 
     void observe(Node*, const Dictionary&, ExceptionState&);
-    Vector<RefPtr<MutationRecord> > takeRecords();
+    WillBeHeapVector<RefPtrWillBeMember<MutationRecord> > takeRecords();
     void disconnect();
     void observationStarted(MutationObserverRegistration*);
     void observationEnded(MutationObserverRegistration*);
-    void enqueueMutationRecord(PassRefPtr<MutationRecord>);
+    void enqueueMutationRecord(PassRefPtrWillBeRawPtr<MutationRecord>);
     void setHasTransientRegistration();
     bool canDeliver();
 
     HashSet<Node*> getObservedNodes() const;
 
+    void trace(Visitor*);
+
 private:
     struct ObserverLessThan;
 
@@ -95,8 +98,8 @@ private:
     void deliver();
 
     OwnPtr<MutationCallback> m_callback;
-    Vector<RefPtr<MutationRecord> > m_records;
-    HashSet<MutationObserverRegistration*> m_registrations;
+    WillBeHeapVector<RefPtrWillBeMember<MutationRecord> > m_records;
+    WillBeHeapHashSet<RawPtrWillBeWeakMember<MutationObserverRegistration> > m_registrations;

[haraken, 2014/04/21 06:00:34]

Does this need to be a hash set of weak members? It looks like
m_observer->observationEnded() is called explicitly when disposing
MutationObserverRegistration.

[sof, 2014/04/21 07:34:05]

Doesn't have to be, but it was requested it be so earlier in this review. Change
back to a strong reference?

[haraken, 2014/04/21 07:41:31]

Or can we keep it a weak member and comment out
MutationObserver::observationEnded() in oilpan builds?

[sof, 2014/04/21 07:43:51]

No, that won't work. Please see comments earlier, I won't repeat, but the
observer need to have an accurate set at all times.

[haraken, 2014/04/21 07:45:46]

ah, remembered, sorry about the confusion. Then it would make sense to make it a
hash set of Members. WeakMember implies that "it will be cleared out when a GC
collects the target", but that's not a behavior we want here. I'm sorry for
bothering you repeatedly.

[sof, 2014/04/21 12:45:16]

I've switched away from weak members on MutationObserver.m_registrations to
reflect that.

     unsigned m_priority;
 };