The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/f53bc613f93665b1c68d98cfd5f1a201dc5d7893

commit f53bc613f93665b1c68d98cfd5f1a201dc5d7893
Author: Mark Cogan <marq@google.com>
Date: Thu Mar 15 16:13:41 2018

[iOS] Page selection control for the tab grid.

This CL creates the custom selection control for the tab grid and
wires it into the TabGridViewController.

There are extensive comments in the TabGridPageSelector class.

Some things to note:

* Labels are used in place of assets for now.

* Dragging the slider in the control isn't possible yet.

* The view controller doesn't yet update the tab counts in the control.

Bug:  804500 ,  804581 
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: If561619091271b7086989f68bb76edb5bd64c16b
Reviewed-on: https://chromium-review.googlesource.com/962791
Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543388}
[modify] https://crrev.com/f53bc613f93665b1c68d98cfd5f1a201dc5d7893/ios/chrome/browser/ui/tab_grid/BUILD.gn
[add] https://crrev.com/f53bc613f93665b1c68d98cfd5f1a201dc5d7893/ios/chrome/browser/ui/tab_grid/tab_grid_page_control.h
[add] https://crrev.com/f53bc613f93665b1c68d98cfd5f1a201dc5d7893/ios/chrome/browser/ui/tab_grid/tab_grid_page_control.mm
[modify] https://crrev.com/f53bc613f93665b1c68d98cfd5f1a201dc5d7893/ios/chrome/browser/ui/tab_grid/tab_grid_top_toolbar.h
[modify] https://crrev.com/f53bc613f93665b1c68d98cfd5f1a201dc5d7893/ios/chrome/browser/ui/tab_grid/tab_grid_top_toolbar.mm
[modify] https://crrev.com/f53bc613f93665b1c68d98cfd5f1a201dc5d7893/ios/chrome/browser/ui/tab_grid/tab_grid_view_controller.mm

The NextAction date has arrived: 2018-03-28