[Extensions] Update ExternalInstallErrorTests to manifest v2

ExternalInstallErrorTests have been updated to manifest v2.
Remove the allowance for manifest v1 extensions.

Bug: 816679
Change-Id: I59bcbcaf0d1d15e6270e485398091f3e714f217b
Reviewed-on: https://chromium-review.googlesource.com/1024609
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553394}
1 file changed