Add COMPONENT to breakpad/OWNERS

R=mark@chromium.org

Review-Url: https://codereview.chromium.org/2856723002
Cr-Original-Commit-Position: refs/heads/master@{#468427}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 6fb00869e878cde5d1eb55fae0397c3bfea4c9c8