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 06ceaca1917f608a98568776fa98ec959f335bf1..d293fccec093e6ff4ddde63b8d2156d4cc7f2108 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 {
 
@@ -69,4 +74,6 @@ $for ARG [[
 }  // namespace internal
 }  // namespace base
 
+#endif  // !defined(ARCH_CPU_X86_64)
+
 #endif  // BASE_BIND_INTERNAL_WIN_H_