Use base/scoped_ptr.h; system_wrappers/interface/scoped_ptr.h is going away

BUG=
R=andrew@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/36229004

Cr-Original-Commit-Position: refs/heads/master@{#8517}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 00b8f6b3643332cce1ee711715f7fbb824d793ca
391 files changed