I'm putting this on hold for now, because I can probably make more progress with other tasks at the moment. 

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/55787a31584a5c2f9f3966bda95dde8dfc38c353

commit 55787a31584a5c2f9f3966bda95dde8dfc38c353
Author: stkhapugin@chromium.org <stkhapugin@chromium.org>
Date: Tue Jul 17 12:55:00 2018

Add a focus/defocus animation to the location bar.

Adds a new animation for the location bar when the
omnibox is focused and defocused.

Bug:  821809 
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I1eeeccc99322bb2ad67e7bd75d24578066451c8f
Reviewed-on: https://chromium-review.googlesource.com/1131749
Reviewed-by: Mark Cogan <marq@chromium.org>
Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575617}
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/location_bar/BUILD.gn
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/location_bar/location_bar_coordinator.h
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/location_bar/location_bar_coordinator.mm
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/location_bar/location_bar_generic_coordinator.h
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/location_bar/location_bar_view_controller.h
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/location_bar/location_bar_view_controller.mm
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/omnibox/BUILD.gn
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/omnibox/omnibox_coordinator.h
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/omnibox/omnibox_coordinator.mm
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.h
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/omnibox/omnibox_text_field_ios.mm
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/omnibox/omnibox_view_controller.h
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/omnibox/omnibox_view_controller.mm
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/orchestrator/BUILD.gn
[add] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/orchestrator/location_bar_animatee.h
[add] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/orchestrator/location_bar_offset_provider.h
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/orchestrator/omnibox_focus_orchestrator.h
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/orchestrator/omnibox_focus_orchestrator.mm
[modify] https://crrev.com/55787a31584a5c2f9f3966bda95dde8dfc38c353/ios/chrome/browser/ui/toolbar/adaptive/primary_toolbar_coordinator.mm

Animation looks good on iPhones but not on iPads.
On iPad omnibox defoucs animation shows the icons overlapping on to the toolbar icons. Not looking good.
iPad Pro with iOS11.4.1

On the iPhone focus/de-focus animation looking good.

Verified on M70.0.3501.0 canary
Device: iPhoneSE, iPhone7Plus, iPhoneX, 
iOS: 11.4.1, 10.3.3, 12.0 beta#4

I filed  crbug.com/867406  to track the reported animation issue. The animation I intended to track in this bug works as expected. 

Thankyou.