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In the beginning, when gn was released, it was used to make performance
tests, as we didn't have many BUILD.gn files.

Now that we have hundreds of them in tree, this is not necessary, as the
performance can be tested with real data.

BUG=94925, 372642
R=brettw@chromium.org,dpranke@chromium.org

Review URL: https://codereview.chromium.org/1534823002

Cr-Commit-Position: refs/heads/master@{#368492}