[Extensions] Update ExtensionManagementApiTest to manifest v2

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

Bug: 816679

Change-Id: I0448ee64cbde9ed8431c30090d1f109e6d655fce
Reviewed-on: https://chromium-review.googlesource.com/1014711
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551749}
3 files changed