Upstream: Launch WebAPK without showing intent picker when user taps link in WebAPK scope
This CL surpresses the intent picker when:
- User navigates via a link
AND
- The URL falls in the scope of a WebAPK
AND
- The WebAPK is the only specialized handler for the URL
BUG=
609122
TEST=ExternalNavigationHandlerTest.*
Committed:
https://crrev.com/b38a7f9839a4ca2fe9032f82173462341dfd1e4b
Cr-Commit-Position: refs/heads/master@{#398946}