Automated commit: libchrome r1553821 uprev

Merge with upstream commit 28d7b470c93085b88dcf1560872567edd01d478a

BUG=None
TEST=sudo emerge libchrome

Change-Id: I35ee27c8387284cebaeb43a723d5995a0fb85f45
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/libchrome/+/7228162
Commit-Queue: Ryo Hashimoto <[email protected]>
Tested-by: ChromeOS Prod (Robot) <[email protected]>
Bot-Commit: ChromeOS Prod (Robot) <[email protected]>