The 1x incognito icon is shifted down 1 px too far.  Move it up.
The 1x incognito icon is shifted down 1 px too far.  Move it up.

This results in the icon being centered within its space and matches what the 2x
icon is already doing.

BUG=none
TEST=none

Review URL: https://codereview.chromium.org/1523713003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#365489}

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