Remove final uses of scoped_ptr in src and crypto

These are preventing us from getting rid of the epatched header
in the libchrome ebuild.

BUG=None
TEST=emerge-{arkham, whirlwind} libweave

Change-Id: Ief89a674886da24a9c98982aa4e0c4dc02be0d4a
Reviewed-on: https://weave-review.googlesource.com/8775
Reviewed-by: Ben Chan <benchan@google.com>
3 files changed