Add "actively refresh services" method to ServiceDiscoveryClient

Add method to ServiceDiscoveryClient that will allow it to actively refresh
stale services when their TTL runs out.

BUG=336883

Review URL: https://codereview.chromium.org/141583010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247857 0039d316-1c4b-4281-b951-d872f2087c98
Make the Convolver unit tests run in a sane amout of time in DEBUG.

Since we are only testing correctness and not performance in Debug, we
can use much smaller images and still get decent coverage.

This reduces the runtime in Debug from 17092ms to 191ms.

BUG=338133

Review URL: https://codereview.chromium.org/149063009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247858 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247858