[iOS] Use extra_attributes in BUILD files.

This CL uses extra_attributes in BUILD files so that these hard-coded
values can be removed from GN.

Bug: 741147, 709289
Change-Id: I2c8a766d7e571fc898277133d343e2e1c0e8028d
Reviewed-on: https://chromium-review.googlesource.com/567619
Commit-Queue: Yuke Liao <liaoyuke@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#494804}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 7c775957071a0c19b8e39ec1087cf8daefe9d00b
1 file changed