Adjust IsRefCountedType to avoid touching static AddRef() and Release()

The previous implementation of it checks if T::AddRef is available, but
it seems to fail on gcc on scoped_refptr, as it has private static
AddRef and Release.

This adjust the check to refer methods of T explicitly to avoid touching
the static member functions.

Change-Id: I7fde97a533df3b4a4b7ddbb0a8f7201c3744bd46
Reviewed-on: https://chromium-review.googlesource.com/933670Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539046}

base/memory/raw_scoped_refptr_mismatch_checker.h

@@ -26,7 +26,9 @@ template <typename T, typename = void>
 struct IsRefCountedType : std::false_type {};
 
 template <typename T>
-struct IsRefCountedType<T, void_t<decltype(&T::AddRef), decltype(&T::Release)>>
+struct IsRefCountedType<T,
+                        void_t<decltype(std::declval<T*>()->AddRef()),
+                               decltype(std::declval<T*>()->Release())>>
     : std::true_type {};
 
 template <typename T>