Add support for base::Closure in the MessageLoop.

base/bind_internal_win.h

Index: base/bind_internal_win.h
diff --git a/base/bind_internal_win.h b/base/bind_internal_win.h
index 976a4d7a0aff6a6b6dc02ab8eb250170b5b0490c..85ba2ae7659f45a1f17372e8bb7733338b9b340f 100644
--- a/base/bind_internal_win.h
+++ b/base/bind_internal_win.h
@@ -15,6 +15,11 @@
 #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 {
 
@@ -180,4 +185,6 @@ struct FunctionTraits<R(__fastcall *)(X1, X2, X3, X4, X5, X6)> {
 }  // namespace internal
 }  // namespace base
 
+#endif  // !defined(ARCH_CPU_X86_64)
+
 #endif  // BASE_BIND_INTERNAL_WIN_H_