Update metrics_library.h to find scoped_ptr.h in <base/memory>.

This is in preparation to the move to a newer libchrome, where
scoped_ptr.h no longer appears in base, just in base/memory.

BUG=chromium-os:16623
TEST=Do the emerge, and then examine /usr/include/metrics/metrics_library.h

Change-Id: I95cd9b52eee216316dd8ea21ecb84101d7a95edf
Reviewed-on: https://gerrit.chromium.org/gerrit/17073


Reviewed-by: Darin Petkov <petkov@chromium.org>
Commit-Ready: Eric Shienbrood <ers@chromium.org>
Reviewed-by: Eric Shienbrood <ers@chromium.org>
Tested-by: Eric Shienbrood <ers@chromium.org>