Move scoped_ptr "free" functions into the webrtc namespace.
Move scoped_ptr "free" functions into the webrtc namespace.

Resolves a conflict with Chromium's scoped_ptr on the recently added
make_scoped_ptr().

TEST=local Chromium Linux build passes.
R=henrike@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/26969004

Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: b787f4c5932cba4c9970b41fcaee48bc5b3d6b53

sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc,sippet/webrtc