Move WebSocket masking benchmarks to net_perftests

Previously WebSocketFrameTestMaskBenchmark.* were included in
net_unittests (with a small number of iterations to avoid slowing down
testing). Move them to net_perftests.

Also remove the command-line option to control the number of iterations,
and use the standard base::PerfTimeLogger output instead of custom logging.

BUG=407445
TEST=net_unittests, net_perftests

Review URL: https://codereview.chromium.org/502353002

Cr-Commit-Position: refs/heads/master@{#292856}
4 files changed