[iOS] Extend ReadingList.* histogram by one year

This CL changes the expire date of the ReadingList histograms to extend
them by one year.

Bug: 972794
Change-Id: I1e7fe03c1ff4264b2855cf5e1829014a0fe405a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1678041
Auto-Submit: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Nik Bhagat <nikunjb@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#673672}
1 file changed