Add the Stability.BrowserExitCodes metric (added in https://chromium.googlesource.com/chromium/src/+/ce04138298b8564e8027c98aee0b28a766ec76da) and a couple of relevant exit codes.

BUG=412384

Review URL: https://codereview.chromium.org/748193002

Cr-Commit-Position: refs/heads/master@{#305327}
1 file changed