[Extensions] Update ExtensionTabsTest to manifest v2

Update ExtensionTabsTest to manifest v2 and remove the allowance
for manifest v1 extensions.

Bug: 816679

Change-Id: Ib718a2169cf42c81f640780884d9a824eca63534
Reviewed-on: https://chromium-review.googlesource.com/1014716
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551771}
1 file changed