[NTPFooter] Rename extension attribution policy

Renaming policy to mention extension instead of theme as a more
accurate term.

Bug: 411428900
Change-Id: If54f500cd04b7e4fa67cbb9a3a744722fe1b6995
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6518824
Reviewed-by: Alex Ilin <[email protected]>
Reviewed-by: Anqing Zhao <[email protected]>
Commit-Queue: Salma Elmahallawy <[email protected]>
Reviewed-by: Victor Gabriel Savu <[email protected]>
Reviewed-by: Salma Elmahallawy <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1459148}
NOKEYCHECK=True
GitOrigin-RevId: a5208725307b89adb96753d15d96bc5d9dbebea4
4 files changed