GitLab

This CL adds initial integration tests of external intent launching,
covering the following cases:
- That an intent is not launched for a vanilla browsing URL.
- That an intent is blocked if navigated to directly.
- That an intent is launched if navigated to via a redirect.

Future CLs will add tests of more cases.

Change-Id: I6141a6aff81acef40155dfaf74d4a11bc10c7a40
Bug: 1029710, 1031465
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2119535
Commit-Queue: Colin Blundell <blundell@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#753558}