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Since the override summary is used in some cases even when a form was
not edited, i.e. kMarkHttpAsParameterDangerous, a different name would
be more descriptive.

Also add checks in the browser test that this summary is present.

Change-Id: I294c68b0e57d2a87b501960185b7c91b2a3e0ce3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1507319Reviewed-by: Emily Stark <estark@chromium.org>
Commit-Queue: Livvie Lin <livvielin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638671}