Adding packets since some WebRTC tests count packets.
Adding packets since some WebRTC tests count packets.

It makes sense to mark them as improvement_direction down since using
less packets to accomplish something is generally a good thing.

BUG=508222

Review URL: https://codereview.chromium.org/1226333002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#338064}

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