Add support for base::Closure in the MessageLoop.

base/bind_internal_win.h.pump

Index: base/bind_internal_win.h.pump
diff --git a/base/bind_internal_win.h.pump b/base/bind_internal_win.h.pump
index 4d213a3691842af879952b86878a29e7e9a86382..644c76dd961c81bd773ed7f4c7c89d30ec8bd59d 100644
--- a/base/bind_internal_win.h.pump
+++ b/base/bind_internal_win.h.pump
@@ -18,6 +18,11 @@ $var MAX_ARITY = 6
 #define BASE_BIND_INTERNAL_WIN_H_
 #pragma once
 
+// In the x64 architecture in Windows, __fastcall, __stdcall, etc, are all
+// the same as __cdecl which would turn the following specializations into
+// multiple definitions.
+#if !defined(ARCH_CPU_X86_64)
+
 namespace base {
 namespace internal {
 
@@ -49,4 +54,6 @@ struct FunctionTraits<R(__fastcall *)($for ARG , [[X$(ARG)]])> {
 }  // namespace internal
 }  // namespace base
 
+#endif  // !defined(ARCH_CPU_X86_64)
+
 #endif  // BASE_BIND_INTERNAL_WIN_H_