[AF Wallet Metadata Sync] Commit changes to WebDB on remote update

This CL adds the missing commit call to the wallet_metadata sync bridge.
The open transaction is normally closed on shutdown but it does not get
closed on Android when the process gets killed.

This situation was never dealt with in any of the autofill sync code.
This CL is thus part of a series of CLs fixing this in all autofill
data types (started by CL 1526262).

Bug: 942435
Change-Id: I3d24adb89b036bddf3f23257e742a8fd93751a3d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1526192
Commit-Queue: Jan Krcal <jkrcal@chromium.org>
Auto-Submit: Jan Krcal <jkrcal@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#641557}
2 files changed