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With SearchProvider, we can suggest URLs as well as queries and show icons at the left of each suggested item.
Also, parts of the suggested query which is not typed by the user are shown bold.

Basically do the same thing as Chrome's AutocompleteController+OmniboxProvider.
Add required resources to athena_resources.

BUG=408050

Review URL: https://codereview.chromium.org/514583002

Cr-Commit-Position: refs/heads/master@{#292350}