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These tests fail to set up correctly on Windows, so running the tests
just crashes. Restore the early outs with an ifdef for windows so we
document where the early out will happen, along with comments.

R=kbr@chromium.org, piman@chromium.org
BUG=595823, 584497

Review URL: https://codereview.chromium.org/1812033002

Cr-Commit-Position: refs/heads/master@{#381802}