[History] Hide clear browsing data button when search field is focused
[History] Hide clear browsing data button when search field is focused

On the history page, the clear browsing data button should disappear
when the search field is active. Add event listener for the search
field coming into focus that updates the clear browsing data button.

BUG=503928

Review URL: https://codereview.chromium.org/1345353005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#352225}

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