Disable toplevel category when trace-to-console
Disable toplevel category when trace-to-console

'toplevel' was 'task' which was excluded when trace-to-console
because it causes deadlock and/or infinite loop of traces.

BUG=568675
TEST=chrome --trace-to-console

Review URL: https://codereview.chromium.org/1540613003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#366393}

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