The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b292e4237a02018f8eafdddcd19709bc87c01364

commit b292e4237a02018f8eafdddcd19709bc87c01364
Author: Sylvain Defresne <sdefresne@chromium.org>
Date: Wed Aug 22 09:46:15 2018

Improve generated Xcode projects

Use the xcode_extra_attributes attribute of create_bundle to set
IPHONEOS_DEPLOYMENT_TARGET, BUNDLE_LOADER and TEST_HOST variables
in the generated Xcode project.

With this change, the deployment target and the host are correctly
set when a project is generated with "gn gen --ide=xcode" and it
is no longer necessary to set the values in convert_gn_xcodeproj.py
script.

Bug:  619072 
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Iae74ce96a188c45553ba7f26357ea29bc081b395
Reviewed-on: https://chromium-review.googlesource.com/1183666
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584982}
[modify] https://crrev.com/b292e4237a02018f8eafdddcd19709bc87c01364/build/config/ios/rules.gni
[modify] https://crrev.com/b292e4237a02018f8eafdddcd19709bc87c01364/ios/build/tools/convert_gn_xcodeproj.py