The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2f53253f8891ba2537d70a9b41054391c82ce0a5

commit 2f53253f8891ba2537d70a9b41054391c82ce0a5
Author: Weidong Guo <weidongg@chromium.org>
Date: Fri Sep 14 16:27:07 2018

Implement dragging to full page when apps grid gap is enabled

Changes:
1. During the dragging to full page, allow inserting placeholder and
   push the last item to next page via
   PagedViewStructure::ClearOverflow().
2. At the end of dragging, add a "page break" item behind the new last
   item and clear the "page break" item behind the old last item in
   local model and server.

Bug:  880977 
Test: AppsGridGapTest.MoveItemToPreviousFullPage

Change-Id: I318d46bb6917846e05f5552b040e45d8fe036319
Reviewed-on: https://chromium-review.googlesource.com/1220946
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Weidong Guo <weidongg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#591366}
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/ash/app_list/app_list_controller_impl.cc
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/ash/app_list/model/app_list_item_list.cc
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/ash/app_list/paged_view_structure.cc
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/ash/app_list/paged_view_structure.h
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/ash/app_list/test/test_app_list_client.h
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/ash/app_list/views/apps_grid_view.cc
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/ash/app_list/views/apps_grid_view_unittest.cc
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/ash/public/interfaces/app_list.mojom
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/chrome/browser/ui/app_list/app_list_client_impl.cc
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/chrome/browser/ui/app_list/app_list_client_impl.h
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/chrome/browser/ui/app_list/app_list_model_updater.h
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/chrome/browser/ui/app_list/chrome_app_list_model_updater.cc
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/chrome/browser/ui/app_list/chrome_app_list_model_updater.h
[modify] https://crrev.com/2f53253f8891ba2537d70a9b41054391c82ce0a5/chrome/browser/ui/app_list/test/fake_app_list_model_updater.h

Issue 885267 has been merged into this issue.