[autofill] Add page language to autofill uploads

This CL adds the detected language of the page to the metadata sent
with a form upload.

Bug: 896719
Change-Id: Ia7fa04dfc8f02af9399b923ca2056a2cb2b04371
Reviewed-on: https://chromium-review.googlesource.com/c/1358634
Commit-Queue: Roger McFarlane <rogerm@chromium.org>
Reviewed-by: anthonyvd <anthonyvd@chromium.org>
Reviewed-by: Fabio Tirelo <ftirelo@chromium.org>
Reviewed-by: Vadym Doroshenko <dvadym@chromium.org>
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#614861}
20 files changed