desktop-pwas: Only check ENABLED extensions when installing new ones

BookmarkApps can only be ENABLED or inexistent, so it doesn't make sense
to query all extensions; querying ENABLED should be enough.

Bug: 916381
Change-Id: I232514d79a5a4413a6e400280b4e1eaec0f3da8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1502314
Commit-Queue: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Reviewed-by: Alexey Baskakov <loyso@chromium.org>
Cr-Commit-Position: refs/heads/master@{#637617}
1 file changed