Revert of Improve DEFINE_STATIC_LOCAL()'s handling of Blink GCed objects.

third_party/WebKit/Source/wtf/StdLibExtras.h

Index: third_party/WebKit/Source/wtf/StdLibExtras.h
diff --git a/third_party/WebKit/Source/wtf/StdLibExtras.h b/third_party/WebKit/Source/wtf/StdLibExtras.h
index 0a6136922b99b607b078c11d07643d65e2a5a05e..5475d3feb7e47a9e4b1ee0552abfadca7f508e13 100644
--- a/third_party/WebKit/Source/wtf/StdLibExtras.h
+++ b/third_party/WebKit/Source/wtf/StdLibExtras.h
@@ -30,7 +30,6 @@
 #include "wtf/Assertions.h"
 #include "wtf/CPU.h"
 #include "wtf/LeakAnnotations.h"
-#include "wtf/TypeTraits.h"
 #include <cstddef>
 
 #if ENABLE(ASSERT)
@@ -60,62 +59,33 @@
 };
 #endif
 
-namespace blink {
-template<typename T>class Persistent;
-};
-
-template<typename T, bool = WTF::IsGarbageCollectedType<T>::value && !WTF::IsPersistentReferenceType<T>::value>
-class StaticLocalWrapper {
-public:
-    using WrapType = T;
-
-    static T& unwrap(T* singleton)
-    {
-        return *singleton;
-    }
-};
-
-template<typename T>
-class StaticLocalWrapper<T, true> {
-public:
-    using WrapType = blink::Persistent<T>;
-
-    static T& unwrap(blink::Persistent<T>* singleton)
-    {
-        ASSERT(singleton);
-        // If this assert triggers, you're supplying an empty ("()") 'Arguments' argument
-        // to DEFINE_STATIC_LOCAL() - it must be the heap object you wish to create
-        // as a static singleton and wrapped up with a Persistent reference.
-        ASSERT(*singleton);
-        return **singleton;
-    }
-};
-
+// A direct static local to a Blink garbage collected objects isn't allowed;
+// must be wrapped up with a persistent reference.
+#define STATIC_ASSERT_FOR_LOCAL_WITH_GARBAGE_COLLECTED_TYPE(Name, Type) \
+    using Name##NoConstType = std::remove_const<Type>::type; \
+    using Name##NoPointerType = std::remove_pointer<Name##NoConstType>::type; \
+    using Name##NoReferenceType = std::remove_reference<Name##NoPointerType>::type; \
+    static_assert(!WTF::IsGarbageCollectedType<Name##NoReferenceType>::value || WTF::IsPersistentReferenceType<Name##NoReferenceType>::value, "Garbage collected static local needs to be wrapped up with a persistent reference")
+
+// Use DEFINE_STATIC_LOCAL() to declare and define a static local variable (static T;)
+// so that it is leaked and its destructors are not called at exit.
+//
+// To cooperate with leak detection, the objects held onto by these local statics
+// will in some cases have to be finalized prior to leak checking. This only applies
+// to static references to Oilpan heap objects and what they transitively hold on to.
+// LEAK_SANITIZER_REGISTER_STATIC_LOCAL() takes care of the details.
+//
 #if ENABLE(ASSERT)
-#define DEFINE_STATIC_LOCAL_CHECK_THREADSAFE_ACCESS(Name) \
+#define DEFINE_STATIC_LOCAL(Type, Name, Arguments)        \
+    STATIC_ASSERT_FOR_LOCAL_WITH_GARBAGE_COLLECTED_TYPE(Name, Type); \
     static StaticLocalVerifier Name##StaticLocalVerifier; \
-    ASSERT(Name##StaticLocalVerifier.isNotRacy())
+    ASSERT(Name##StaticLocalVerifier.isNotRacy());        \
+    static Type& Name = *LEAK_SANITIZER_REGISTER_STATIC_LOCAL(Type, new Type Arguments)
 #else
-#define DEFINE_STATIC_LOCAL_CHECK_THREADSAFE_ACCESS(Name)
-#endif
-
-// Use DEFINE_STATIC_LOCAL() to declare and define a static local variable
-// (static T;) so that it is leaked and its destructors are not called at exit.
-// T may also be a Blink garbage collected object, in which case it is
-// wrapped up by an off-heap Persistent<T> reference to the object, keeping
-// it alive across GCs.
-//
-// To cooperate with leak detection(LSan) for Blink garbage collected objects,
-// the objects owned by persistent local statics will in some cases have to be
-// finalized prior to leak checking. This only applies to static references to
-// Blink heap objects and what they transitively hold on to. Hence the
-// LEAK_SANITIZER_REGISTER_STATIC_LOCAL() use, it taking care of the grungy
-// details.
-//
-#define DEFINE_STATIC_LOCAL(Type, Name, Arguments)                    \
-    DEFINE_STATIC_LOCAL_CHECK_THREADSAFE_ACCESS(Name);                \
-    using WrappedTypeFor##Name = StaticLocalWrapper<Type>::WrapType;  \
-    static Type& Name = StaticLocalWrapper<Type>::unwrap(LEAK_SANITIZER_REGISTER_STATIC_LOCAL(WrappedTypeFor##Name, new WrappedTypeFor##Name Arguments))
+#define DEFINE_STATIC_LOCAL(Type, Name, Arguments) \
+    STATIC_ASSERT_FOR_LOCAL_WITH_GARBAGE_COLLECTED_TYPE(Name, Type); \
+    static Type& Name = *LEAK_SANITIZER_REGISTER_STATIC_LOCAL(Type, new Type Arguments)
+#endif
 
 // Use this to declare and define a static local pointer to a ref-counted object so that
 // it is leaked so that the object's destructors are not called at exit.