Add a util memory-eater-locked to allocate non-swappable memory. It can be useful for memory related test. BUG=chromium:821046 TEST=manual Change-Id: I45f790e3957b8552977608d7a7d3ce53b13431cb Reviewed-on: https://chromium-review.googlesource.com/988892 Commit-Ready: Cheng-Yu Lee <[email protected]> Tested-by: Cheng-Yu Lee <[email protected]> Reviewed-by: Chung-yih Wang <[email protected]>