Notes:
- Other platforms to follow later.
- This follows Chromium practice, that mostly uses this feature these days.
- The statically linked-in startup data will stay. So whoever prefers
  the old way just needs to set the flag differently.

Reland crrev.com/959693002, once crrev.com/960883003 is in.

R=machenbach@chromium.org
BUG=

Review URL: https://codereview.chromium.org/956373002

Cr-Commit-Position: refs/heads/master@{#26980}