GitLab

Removes ScopedVector in favor of vector<unique_ptr>  in presentation_service_impl and related files as requested in Avi's
comment in https://codereview.chromium.org/2562603002/

BUG=554289

Review-Url: https://codereview.chromium.org/2574673002
Cr-Commit-Position: refs/heads/master@{#439052}