You don't hear as much about developer tools being sunset because they rarely impact as many people and that makes less interesting news.
Examples include: AngularJS (replaced by a rewrite of angular effectively), GWT (donated as 'open source' with minimal continued google involvement), basically 90% of all 20% projects by googlers that weren't official google stuff (too many examples to name, practically all of them), the xmpp api for google talk (and all associated library code, including some open source xmpp extensions, libjingle), tons of chrome and android libraries that were killed/deprecated as part of new versions not using them, ARC (https://en.wikipedia.org/wiki/Google_App_Runtime_for_Chrome), the caldav API for google calendar and any associated libraries...
I could go on, but the majority of the relevant examples are the 20% projects that never made it, and I'd rather not list any of those since they're largely single-person projects and it's kinda personal to comment on any of em.