GitLab

This CL changes CSPHandler so that it can be used for both extensions and
platform apps without creating a different instance for the two. This helps
simplify the code.

BUG=914224

Change-Id: Ib99fd306071514706d6a3a6b032870f016736a9e
Reviewed-on: https://chromium-review.googlesource.com/c/1394912Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Karan Bhatia <karandeepb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#619807}