base::ListValue::Append cleanup: pass unique_ptr instead of the released pointer.

BUG=581865
R=thakis@chromium.org
TBR=jochen@chromium.org,junov@chromium.org,rdevlin.cronin@chromium.org,rogerta@chromium.org,sky@chromium.org,xhwang@chromium.org,wez@chromium.org,zea@chromium.org

Review-Url: https://codereview.chromium.org/2051663003
Cr-Commit-Position: refs/heads/master@{#398941}
97 files changed