Use default flag style for multi-value flags if no switches have been passed.
Use default flag style for multi-value flags if no switches have been passed.

BUG=None
TEST=Multi value experiments on chrome://flags have same style as single value experiments when no overriding flags have been passed.

Review URL: https://codereview.chromium.org/1191493004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#335138}

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