Issue 809282 has been merged into this issue.

Could crrev.com/854701 affect this?

fix is ready, 

crrev.com/c/854701 does change the code path of setting item icons, but I'm not sure how relevant it is.

Why does it only happen to Play Store? Is it somewhat special?

That is not only Play Store icon problem. It may happen with any app. Play Store has just 100% repro rate. I saw missing icon on random apps. Details in CL: crrev.com/c/902610

Oh thanks for the fix!

 Issue 809373  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e7ded6a127d060da95ae7fe3c8f622d268f95398

commit e7ded6a127d060da95ae7fe3c8f622d268f95398
Author: khmel <khmel@google.com>
Date: Tue Feb 06 17:30:58 2018

Fix missing default app icons in launcher.

Setting app launcher icon is multi-step process. At first step we set
default (or pre-loaded icon) and then try to fetch, decode and load
actual icon. For some app fetch/decode step may be skipped. At this case
icon is left what was set at first step. With recent refactoring, app
launcher icon and chrome app icon were split and synced via updater.
App launcher item is created after Chrome app item. Some attributes from
Chrome app are passed via metadata but not the icon.
This CL sets the icon from Chrome app item to app laucnher item at the
moment of creation app launcher item.

Bug:  809269 
Test: Manually
Change-Id: Iee8f5701d41f2ea19533d7df3edcc3898d606044
Reviewed-on: https://chromium-review.googlesource.com/902610
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Yury Khmel <khmel@google.com>
Cr-Commit-Position: refs/heads/master@{#534701}
[modify] https://crrev.com/e7ded6a127d060da95ae7fe3c8f622d268f95398/chrome/browser/ui/app_list/chrome_app_list_model_updater.cc