From a privacy perspective, when app is removed, we should auto-clear all records associated to this app. This bug is created to discuss how to design and implement this auto-clear behavior in PowerStats API.

In Bug 854200 [1], I porposed to catch the "webapps-clear-data" notification when app is removed and use a preference to control whether we should auto-clean the power usage record of that app. Jonas also suggested we can observe another notification to catch the event of removing app instead of observing "webapps-clear-data". Hi Jonas, could you tell me that notification name? Thanks. [1] https://bugzilla.mozilla.org/show_bug.cgi?id=854200#c59

Hi Jonas: Did you mean we can listen the "webapps-uninstall" notification [1]? [1] http://mxr.mozilla.org/mozilla-central/source/dom/apps/src/Webapps.jsm#3292

Yes, please use "webapps-uninstall" instead.

Hi Vicamo and Ethan: For privacy concern, we want to delete all related data and record when an app is unistalled. This patch clears all stats of an app saved in DB and statsCache when the b2g process receives the "webapps-uninstall" notification.

Hi Vicamo and Ethan: This patch adds a new xpcshell test to test _db.processAppUninstall(). And, here is the try result: https://tbpl.mozilla.org/?tree=Try&rev=ab8ffc25aaa5

Firefox OS is not being worked on