The first step should also include the processing of archive files in abandoned directory, after which the abandoned directory should be empty.

more context from the CL:

There will be a new task for doing:
Delete all temporary pages (and their files) if the file path is in abandoned dir.

And this will be executed when the chrome starts for the first time, and it shouldn't be executed routinely as other implemented steps.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e00be28bb57af66640efa959fc0587182b20d468

commit e00be28bb57af66640efa959fc0587182b20d468
Author: Yafei Duan <romax@chromium.org>
Date: Tue Nov 21 04:34:58 2017

[Offline Pages] Separate legacy pages clearing from Consistency Check.

Removed the clearing of the pages in legacy archives directory from the
temporary pages consistency check, and created a new task for it.
The new task should only be executed when there is a Chrome version
upgrade detected within Offline Page Model, which will be introduced in
the future.

Bug:  770871 
Change-Id: I6a6a4c5910da16c11281242dab424ceae4636dbe
Reviewed-on: https://chromium-review.googlesource.com/710525
Commit-Queue: Yafei Duan <romax@chromium.org>
Reviewed-by: Filip Gorski <fgorski@chromium.org>
Cr-Commit-Position: refs/heads/master@{#518115}
[modify] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/BUILD.gn
[add] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/clear_legacy_temporary_pages_task.cc
[add] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/clear_legacy_temporary_pages_task.h
[add] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/clear_legacy_temporary_pages_task_unittest.cc
[modify] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/clear_storage_task_unittest.cc
[modify] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/offline_page_model_taskified_unittest.cc
[add] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/offline_page_test_util.cc
[add] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/offline_page_test_util.h
[modify] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/temporary_pages_consistency_check_task.cc
[modify] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/temporary_pages_consistency_check_task.h
[modify] https://crrev.com/e00be28bb57af66640efa959fc0587182b20d468/components/offline_pages/core/model/temporary_pages_consistency_check_task_unittest.cc