[wrapper-tracing] Simplify tracing by forbidding tracing from within mixins

third_party/WebKit/Source/platform/heap/GarbageCollected.h

Index: third_party/WebKit/Source/platform/heap/GarbageCollected.h
diff --git a/third_party/WebKit/Source/platform/heap/GarbageCollected.h b/third_party/WebKit/Source/platform/heap/GarbageCollected.h
index e814c8c0d1a0b3a518b12577051c49a1fc7a0c34..58c9313c60b75b7ea196bdd9396ef077543d2b0e 100644
--- a/third_party/WebKit/Source/platform/heap/GarbageCollected.h
+++ b/third_party/WebKit/Source/platform/heap/GarbageCollected.h
@@ -14,10 +14,8 @@ namespace blink {
 
 template <typename T>
 class GarbageCollected;
-class HeapObjectHeader;
 class InlinedGlobalMarkingVisitor;
 class TraceWrapperBase;
-class WrapperVisitor;
 
 // GC_PLUGIN_IGNORE is used to make the plugin ignore a particular class or
 // field when checking for proper usage.  When using GC_PLUGIN_IGNORE
@@ -77,11 +75,7 @@ class PLATFORM_EXPORT GarbageCollectedMixin {
   virtual void trace(Visitor*) {}
   virtual void adjustAndMark(InlinedGlobalMarkingVisitor) const = 0;
   virtual void trace(InlinedGlobalMarkingVisitor);
-  virtual void adjustAndMarkAndTraceWrapper(const WrapperVisitor*) const = 0;
-  virtual void adjustAndMarkWrapperNoTracing(const WrapperVisitor*) const = 0;
-  virtual void adjustAndTraceMarkedWrapper(const WrapperVisitor*) const = 0;
   virtual bool isHeapObjectAlive() const = 0;
-  virtual HeapObjectHeader* adjustAndGetHeapObjectHeader() const = 0;
 };
 
 #define DEFINE_GARBAGE_COLLECTED_MIXIN_METHODS(VISITOR, TYPE)                 \
@@ -104,47 +98,6 @@ class PLATFORM_EXPORT GarbageCollectedMixin {
                                                                               \
  private:
 
-#define DEFINE_GARBAGE_COLLECTED_MIXIN_WRAPPER_METHODS(TYPE)                 \
- private:                                                                    \
-  typedef WTF::IsSubclassOfTemplate<typename std::remove_const<TYPE>::type,  \
-                                    blink::GarbageCollected>                 \
-      IsSubclassOfGarbageCollected;                                          \
-                                                                             \
- public:                                                                     \
-  void adjustAndMarkAndTraceWrapper(const WrapperVisitor* visitor)           \
-      const override {                                                       \
-    static_assert(                                                           \
-        IsSubclassOfGarbageCollected::value,                                 \
-        "only garbage collected objects can have garbage collected mixins"); \
-    return AdjustAndMarkTrait<TYPE>::markAndTraceWrapper(                    \
-        visitor, static_cast<const TYPE*>(this));                            \
-  }                                                                          \
-  void adjustAndMarkWrapperNoTracing(const WrapperVisitor* visitor)          \
-      const override {                                                       \
-    static_assert(                                                           \
-        IsSubclassOfGarbageCollected::value,                                 \
-        "only garbage collected objects can have garbage collected mixins"); \
-    return AdjustAndMarkTrait<TYPE>::markWrapperNoTracing(                   \
-        visitor, static_cast<const TYPE*>(this));                            \
-  }                                                                          \
-  void adjustAndTraceMarkedWrapper(const WrapperVisitor* visitor)            \
-      const override {                                                       \
-    static_assert(                                                           \
-        IsSubclassOfGarbageCollected::value,                                 \
-        "only garbage collected objects can have garbage collected mixins"); \
-    AdjustAndMarkTrait<TYPE>::traceMarkedWrapper(                            \
-        visitor, static_cast<const TYPE*>(this));                            \
-  }                                                                          \
-  HeapObjectHeader* adjustAndGetHeapObjectHeader() const override {          \
-    static_assert(                                                           \
-        IsSubclassOfGarbageCollected::value,                                 \
-        "only garbage collected objects can have garbage collected mixins"); \
-    return AdjustAndMarkTrait<TYPE>::heapObjectHeader(                       \
-        static_cast<const TYPE*>(this));                                     \
-  }                                                                          \
-                                                                             \
- private:
-
 // A C++ object's vptr will be initialized to its leftmost base's vtable after
 // the constructors of all its subclasses have run, so if a subclass constructor
 // tries to access any of the vtbl entries of its leftmost base prematurely,
@@ -204,7 +157,6 @@ class PLATFORM_EXPORT GarbageCollectedMixin {
   DEFINE_GARBAGE_COLLECTED_MIXIN_METHODS(blink::Visitor*, TYPE)              \
   DEFINE_GARBAGE_COLLECTED_MIXIN_METHODS(blink::InlinedGlobalMarkingVisitor, \
                                          TYPE)                               \
-  DEFINE_GARBAGE_COLLECTED_MIXIN_WRAPPER_METHODS(TYPE)                       \
   DEFINE_GARBAGE_COLLECTED_MIXIN_CONSTRUCTOR_MARKER(TYPE)                    \
  public:                                                                     \
   bool isHeapObjectAlive() const override {                                  \