Reduce the size of security_context.h

security_context.h is used in 2,700+ compilation units. crrev.com/594074
increased its pre-processed size by 1.32MB, and this CL fixes it.

Bug: 242216, 888668
Change-Id: I623ad22e5351328f934a0b1cd7caece6b4b07944
Reviewed-on: https://chromium-review.googlesource.com/1256470
Reviewed-by: Daniel Bratell <bratell@opera.com>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#595757}
1 file changed