Chrome writes a "lastrun" value to the registry to serve as a means for other components to know when the last time Chrome was run (e.g., gcapi). This value is written during browser process startup, even for silent background launches. Since these launches don't represent the user interacting with Chrome, they should be excluded.

It's also worth considering if "last browser startup" is even the right thing to measure. Perhaps "last user interaction" makes more sense. Does interacting with an app or extension (e.g., Hangouts) count as running Chrome? If not, is there anything other than interacting with a browser window that should count?

It feels like "lastrun" and "dr" (issue 489821) be driven by the same policy, and therefore be in sync.