[Manifest] Add metrics recording.

This is recording whether the manifest fetching was successful or failed.
It is also recording which properties are present in the parsed Manifest
and whether the output of the parsing is empty.
Finally, it is recording whether a Manifest was used when creating a
shortcut.

BUG=366145

Review URL: https://codereview.chromium.org/622813002

Cr-Commit-Position: refs/heads/master@{#298575}
8 files changed