touch_noise_filter: replace scoped_ptr with std::unique_ptr

scoped_ptr from libchrome has been deprecated in favor of C++11
std::unique_ptr.

BUG=chromium:672314
TEST=Run unit tests.

Change-Id: I2a1e0a33794fcf0c0e13edfe36155c4bef21d2dd
Reviewed-on: https://chromium-review.googlesource.com/418478
Commit-Ready: Ben Chan <benchan@chromium.org>
Tested-by: Ben Chan <benchan@chromium.org>
Reviewed-by: Mike Frysinger <vapier@chromium.org>
2 files changed