GitLab

Remove the std::unique_ptr<> members from ExternalInstallInfoFile and
ExternalInstallInfoUpdateUrl. These were used to hold the version and
url members, but each of these will never be null and are cheaply 
copyable (or, in the case of GURL, movable), so have no reason to
be pointers.

Bug: 770007
Change-Id: I4b9c3ef8c9888a2d460ab082a9fa3339423a5ee6
Reviewed-on: https://chromium-review.googlesource.com/691045
Commit-Queue: Devlin <rdevlin.cronin@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505398}