Currently, ChromeOS uses gmock 1.7, which is the latest version
before googlemock project is merged into googletest.

gmock 1.7 does not contain some important support, specifically for C++11, such as returning move-only-type, etc.
https://github.com/google/googletest/blob/master/googlemock/docs/CookBook.md#mocking-methods-that-use-move-only-types

It'd be great if we could use those features.

cf) Tracking issue in gentoo.
https://bugs.gentoo.org/show_bug.cgi?id=602218