Undo a68594234262.
Undo a68594234262.

The buffer sizing logic was correct to start with. I don’t know why I
misread it. It should say “if this would resize to receive a large
message, use the entire allocation rounded up to full page size,
otherwise, only use the space expected for a message.”

TEST=util_test
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/760573003

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