Introduce ResourceOwner to simplify ResoureClient implementation.

This change introduces ResourceOwner helper class and
deploys it to several ResourceClient implementations.
This automates removeClient() for such classes and also provides
some functions to get rid of boilerplates.

BUG=none
TEST=none
R=japhet@chromium.org, abarth, eseidel

Review URL: https://codereview.chromium.org/106363003

git-svn-id: svn://svn.chromium.org/blink/trunk@163844 bbb929c8-8fbe-4397-9dbb-9b2b20218538