Missing header for VS1029 (for commit 8c58491d)

This recently broke in VS2019 (weak_ptr and shared_ptr aren't included).

Change-Id: I88edffa3e965c02d0db83e2efd0977cf86c96800
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/38023
Commit-Queue: Carl Woffenden <cwoffenden@gmail.com>
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

src/dawn_wire/client/Device.h

@@ -23,6 +23,7 @@
 #include "dawn_wire/client/ObjectBase.h"
 
 #include <map>
+#include <memory>
 
 namespace dawn_wire { namespace client {