Revert of Implement WTF::WeakPtr in terms of base::WeakPtr

third_party/WebKit/Source/wtf/Functional.h

Index: third_party/WebKit/Source/wtf/Functional.h
diff --git a/third_party/WebKit/Source/wtf/Functional.h b/third_party/WebKit/Source/wtf/Functional.h
index cac8662d7a42a76be48706c6446394a77ed6baef..97d156086f32ca4bcd6157581821fc1431e82daf 100644
--- a/third_party/WebKit/Source/wtf/Functional.h
+++ b/third_party/WebKit/Source/wtf/Functional.h
@@ -35,6 +35,7 @@
 #include "wtf/RefPtr.h"
 #include "wtf/ThreadSafeRefCounted.h"
 #include "wtf/TypeTraits.h"
+#include "wtf/WeakPtr.h"
 #include <utility>
 
 namespace blink {
@@ -238,6 +239,9 @@
 namespace base {
 
 template <typename T>
+struct IsWeakReceiver<WTF::WeakPtr<T>> : std::true_type {};
+
+template <typename T>
 struct BindUnwrapTraits<WTF::RefPtr<T>> {
     static T* Unwrap(const WTF::RefPtr<T>& wrapped)
     {