Move assignment operator of both classes contained a memory leak. Changed type of mMessage from mutable std::string *to mutable std::unique_ptr<std::string> BUG=angleproject:1264 Change-Id: I7d1419b2e9f385b36afebfd6371983be33ee9e61 Reviewed-on: https://chromium-review.googlesource.com/319520Reviewed-by: Geoff Lang <geofflang@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org> Tryjob-Request: Tibor Ouden, den <tibordenouden@gmail.com> Tested-by: Jamie Madill <jmadill@chromium.org>
