What steps will reproduce the problem?
1. Try to build base_unittests with gcc

What is the expected result?
Tests build and pass.

What happens instead of that?
The target fails to compile, because gcc does not allow large values to be specified when using alignas (see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68267)

The test did compile and work in chromium 59. The problem was introduced in bug 688061 (https://codereview.chromium.org/2670873002/)