Disable Chrome's default headers & footers in headless print-to-pdf
There is an option available in latest Google Chrome Canary builds for this. Use the --print-to-pdf-no-header
option.
canary --headless --disable-gpu --run-all-compositor-stages-before-draw --print-to-pdf-no-header --print-to-pdf=example.pdf http://example.com
ref: source code