Reauthorize Keychain to Replace Developer ID Certificate

This adds the code to reauthorize the Safe Storage Keychain entry to prepare for
replacing Chrome's Developer ID certificate. This signs Chrome with a
new designated requirement (DR), that includes both the current and new
certificate. It then deletes and re-adds our safe storage entry to the
keychain. This is because a keychain entry's ACL is the application's DR
by default, and an app cannot modify the ACL, but it can delete its own
item. The re-authorization code is not yet called at Chrome's launch.

BUG=629906

Review-Url: https://codereview.chromium.org/2721333005
Cr-Commit-Position: refs/heads/master@{#454649}
7 files changed