[oilpan] Fix iterators over member collections to return Result<T>

Source/heap/Handle.h

Index: Source/heap/Handle.h
diff --git a/Source/heap/Handle.h b/Source/heap/Handle.h
index b175a9140fcdda2ac6c280f1916f416f5de6822b..d6bafcb7152dc76bbbf3bf99ec6373c2bc63bfb9 100644
--- a/Source/heap/Handle.h
+++ b/Source/heap/Handle.h
@@ -691,6 +691,15 @@ public:
     {
     }
 
+    template<typename U>

[Mads Ager (chromium), 2013/08/16 10:23:41]

We really shouldn't be using this unless we really know what we are doing. Can
we make this private and only accessible from the iterators?

[Erik Corry, 2013/08/16 11:39:27]

Done.

+    Result(const Member<U>* other)
+        : m_raw(other->raw())
+#ifndef NDEBUG
+        , m_doNotAllocate()
+#endif
+    {
+    }
+
     ~Result()
     {
     }
@@ -729,6 +738,13 @@ public:
         return *this;
     }
 
+    template<typename U>
+    Result& operator=(const Member<U>* other)
+    {
+        COMPILE_ASSERT(!sizeof(T*), Result_should_never_be_assigned_to);
+        return *this;
+    }
+
     template<typename U> bool operator==(const U* other) const { return other == m_raw; }
     template<typename U> bool operator!=(const U* other) const { return other != m_raw; }
 
@@ -814,6 +830,7 @@ private:
     mutable NoAllocation m_doNotAllocate;
 #endif
 
+    template<typename U> friend void Visitor::visit(const class Result<U>&);
     template<typename U> friend class Persistent;
     template<typename U> friend class Handle;
     template<typename U> friend class Member;
@@ -1460,6 +1477,12 @@ template<typename T> struct HashTraits<WebCore::Member<T> > : SimpleClassHashTra
     // the two types can be merged into PassInType.
     typedef const typename WebCore::Handle<T>& PeekInType;
     typedef const typename WebCore::Handle<T>& PassInType;
+    typedef WebCore::Result<T> IteratorGetType;
+    typedef WebCore::Result<T> IteratorConstGetType;
+    typedef WebCore::Result<T> IteratorReferenceType;
+    typedef WebCore::Result<T> IteratorConstReferenceType;
+    static IteratorReferenceType getToReferenceConversion(IteratorGetType x) { return x; }
+    static IteratorConstReferenceType getToReferenceConstConversion(IteratorConstGetType x) { return x; }
     // FIXME(oilpan): Similarly, there is no need for a distinction between
     // PeekType and PassOutType without reference counting.
     typedef typename WebCore::Result<T> PeekType;