blink_gc_plugin: detect singletons with embedded ScriptWrappables.

tools/clang/blink_gc_plugin/tests/legacy_naming/heap/stubs.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 HEAP_STUBS_H_
 #define HEAP_STUBS_H_
 
 #include "stddef.h"
 
 #define WTF_MAKE_FAST_ALLOCATED                 \
@@ skipping 170 matching lines @@
 
 #define ALLOW_ONLY_INLINE_ALLOCATION()    \
     public:                               \
     void* operator new(size_t, void*);    \
     private:                              \
     void* operator new(size_t) = delete;
 
 #define GC_PLUGIN_IGNORE(bug)                           \
     __attribute__((annotate("blink_gc_plugin_ignore")))
 
+#define BLINK_STATIC_SINGLETON() \
+  __attribute__((annotate("blink_gc_singleton_type")))
+
 #define USING_GARBAGE_COLLECTED_MIXIN(type)                     \
 public:                                                         \
     virtual void adjustAndMark(Visitor*) const override { }     \
     virtual bool isHeapObjectAlive(Visitor*) const override { return 0; }
 
 #define EAGERLY_FINALIZED() typedef int IsEagerlyFinalizedMarker
 
 template<typename T> class GarbageCollected { };
 
 template<typename T>
@@ skipping 11 matching lines @@
 
 template<typename T> class WeakMember {
 public:
     operator T*() const { return 0; }
     T* operator->() { return 0; }
     bool operator!() const { return false; }
 };
 
 template<typename T> class Persistent {
 public:
-    operator T*() const { return 0; }
-    T* operator->() { return 0; }
-    bool operator!() const { return false; }
+ explicit Persistent(T*) {}
+ operator T*() const { return 0; }
+ T* operator->() { return 0; }
+ bool operator!() const { return false; }
 };
 
 template<typename T> class WeakPersistent {
 public:
     operator T*() const { return 0; }
     T* operator->() { return 0; }
     bool operator!() const { return false; }
 };
 
 template<typename T> class CrossThreadPersistent {
@@ skipping 55 matching lines @@
     virtual void adjustAndMark(Visitor*) const = 0;
     virtual bool isHeapObjectAlive(Visitor*) const = 0;
     virtual void trace(Visitor*) { }
 };
 
 template<typename T>
 struct TraceIfNeeded {
     static void trace(Visitor*, T*);
 };
 
+class ScriptWrappable {};
 }
 
 namespace WTF {
 
 template<typename T>
 struct VectorTraits<blink::Member<T> > {
     static const bool needsDestruction = false;
 };
 
 }
 
 #endif