This also removes the destructor of the class in question, which removed
any added decorator from the graph. However the adding of the decorator
happens explicitly, so symmetry suggests that removal should also happen
explicitly instead of implicitly in the destructor.

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/1914473002

Cr-Commit-Position: refs/heads/master@{#35732}