Oilpan: add explicit Persistent<T>(T&) and Member<T>(T&) constructors.

Source/platform/heap/Handle.h

 /*
  * Copyright (C) 2014 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 198 matching lines @@
 private:
     PersistentAnchor() : PersistentNode(TraceMethodDelegate<PersistentAnchor, &PersistentAnchor::trace>::trampoline)
     {
         m_next = this;
         m_prev = this;
     }
 
     friend class ThreadState;
 };
 
+#ifndef NDEBUG
+    // For global persistent handles we cannot check that the
+    // pointer is in the heap because that would involve
+    // inspecting the heap of running threads.
+#define ASSERT_IS_VALID_PERSISTENT_POINTER(pointer) \
+    bool isGlobalPersistent = WTF::IsSubclass<RootsAccessor, GlobalPersistents>::value; \
+    ASSERT(!pointer || isGlobalPersistent || ThreadStateFor<ThreadingTrait<T>::Affinity>::state()->contains(pointer))
+#else
+#define ASSERT_IS_VALID_PERSISTENT_POINTER(pointer)
+#endif
+
 template<typename T>
 class CrossThreadPersistent;
 
 // Persistent handles are used to store pointers into the
 // managed heap. As long as the Persistent handle is alive
 // the GC will keep the object pointed to alive. Persistent
 // handles can be stored in objects and they are not scoped.
 // Persistent handles must not be used to contain pointers
 // between objects that are in the managed heap. They are only
 // meant to point to managed heap objects from variables/members
@@ skipping 15 matching lines @@
     }
 
     Persistent(std::nullptr_t) : m_raw(0)
     {
         COMPILE_ASSERT_IS_GARBAGE_COLLECTED(T, NonGarbageCollectedObjectInPersistent);
     }
 
     Persistent(T* raw) : m_raw(raw)
     {
         COMPILE_ASSERT_IS_GARBAGE_COLLECTED(T, NonGarbageCollectedObjectInPersistent);
-#ifndef NDEBUG
-        // For global persistent handles we cannot check that the
-        // pointer is in the heap because that would involve
-        // inspecting the heap of running threads.
-        bool isGlobalPersistent = WTF::IsSubclass<RootsAccessor, GlobalPersistents>::value;
-        ASSERT(!raw || isGlobalPersistent || ThreadStateFor<ThreadingTrait<T>::Affinity>::state()->contains(raw));
-#endif
+        ASSERT_IS_VALID_PERSISTENT_POINTER(m_raw);
+    }
+
+    explicit Persistent(T& raw) : m_raw(&raw)
+    {
+        COMPILE_ASSERT_IS_GARBAGE_COLLECTED(T, NonGarbageCollectedObjectInPersistent);
+        ASSERT_IS_VALID_PERSISTENT_POINTER(m_raw);
     }
 
     Persistent(const Persistent& other) : m_raw(other)
     {
         COMPILE_ASSERT_IS_GARBAGE_COLLECTED(T, NonGarbageCollectedObjectInPersistent);
     }
 
     template<typename U>
     Persistent(const Persistent<U, RootsAccessor>& other) : m_raw(other) { }
 
@@ skipping 154 matching lines @@
     Member(std::nullptr_t) : m_raw(0)
     {
         COMPILE_ASSERT_IS_GARBAGE_COLLECTED(T, NonGarbageCollectedObjectInMember);
     }
 
     Member(T* raw) : m_raw(raw)
     {
         COMPILE_ASSERT_IS_GARBAGE_COLLECTED(T, NonGarbageCollectedObjectInMember);
     }
 
+    explicit Member(T& raw) : m_raw(&raw)
+    {
+        COMPILE_ASSERT_IS_GARBAGE_COLLECTED(T, NonGarbageCollectedObjectInMember);
+    }
+
     Member(WTF::HashTableDeletedValueType) : m_raw(reinterpret_cast<T*>(-1))
     {
         COMPILE_ASSERT_IS_GARBAGE_COLLECTED(T, NonGarbageCollectedObjectInMember);
     }
 
     bool isHashTableDeletedValue() const { return m_raw == reinterpret_cast<T*>(-1); }
 
     template<typename U>
     Member(const Persistent<U>& other) : m_raw(other) { }
 
@@ skipping 509 matching lines @@
 };
 
 template<typename T, typename U>
 struct NeedsTracing<HashMap<T, U> > {
     static const bool value = false;
 };
 
 } // namespace WTF
 
 #endif