Hook up NetLog for CookieStore on iOS

This is to help with investigating cookies bugs.

This is based on rdsmith@'s CL at
https://chromium-review.googlesource.com/c/chromium/src/+/925181

Bug: 801910
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Ia0fbfca17a8a8ad76cbcc4e1ae46330b3f706ea0
Reviewed-on: https://chromium-review.googlesource.com/1175921
Commit-Queue: Helen Li <[email protected]>
Reviewed-by: Rohit Rao <[email protected]>
Cr-Commit-Position: refs/heads/master@{#584737}
13 files changed