[ios] add url_load_params to url loading service.

Leaving use of OpenNewTabCommand and ChromeLoadParams alone for now,
but opened the road to deprecate their use in the loader.

Bug: 907527
Change-Id: Ie20e7ccaf348b112ee39406ea573902957ef58bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1503261
Commit-Queue: David Jean <djean@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#640288}
24 files changed