[Merge-M54] arc: Make Play Store item persistent in app list.

[Merge-M54]  arc: Make Play Store item persistent in app list.

This uses default & OEM Arc apps support to implement Play
Store as default item. Clicking it starts OptIn process or
launch Play Store if Arc is already opted in. This CL also
updates default apps implementation by adding install and
last launch time support to correct representation of
default items in the recent list.

BUG=b/31242721
BUG=643686
TEST=Manually on device.

TBR=reviewer@chromium.org
NOTRY=true
NOPRESUBMIT=true

Review-Url: https://codereview.chromium.org/2308643002
Cr-Commit-Position: refs/heads/master@{#416965}

(cherry picked from commit ffb325645bf768c7c83a7008f40c07ec5b29de8a)

[khmel, 2016-09-09 20:29:51]

The CQ bit was checked by khmel@chromium.org

[commit-bot: I haz the power, 2016-09-09 20:30:14]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-09-09 20:51:37]

Committed patchset #1 (id:1)