Reland "[Extensions] Remove manifest v1 support for accessible resources"

This is a reland of 7a1b3bb0f7aa68093639da976f3b4ecedd4585d8

TBR=karandeepb@chromium.org (reland with no changes)

Original change's description:
> [Extensions] Remove manifest v1 support for accessible resources
>
> In manifest version 1, all extension resources were considered
> accessible by the web (i.e., could be embedded within or
> requested by a web page). In manifest v2, only resources
> explicitly specified in the web_accessible_resources key are
> accessible. Remove support for manifest v1, and always check
> the web accessible resources.
>
> Update unit tests to migrate relevant tests and remove tests for
> manifest v1-specific behavior.
>
> Bug: 816677, 816679
> Change-Id: Id0dd3ef75cd5d49e3f87e45ac3a8b19a00391146
> Reviewed-on: https://chromium-review.googlesource.com/953177
> Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
> Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#545898}

Bug: 816677, 816679
Change-Id: Ic26fb161878df83c40e92e2fa19dd3f698b4d62c
Reviewed-on: https://chromium-review.googlesource.com/981090
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546215}
12 files changed