Currently, all widgets request selection change notifications to IMEContentObserver. Additionally, IMEContentObserver needs to listen selection changes for caching latest selection for eQuerySelectedText. Therefore, it doesn't make sense to keep defining nsIMEUpdatePreference::NOTIFY_SELECTION_CHANGE.
If widgets didn't need selection change notifications, they could just ignore the unnecessary notifications.
Note that all widgets don't need selection change notifications if a plugin has focus and IMEContentObserver cannot observe selection changes in the plugin. Therefore, if IMEContentObserver is initialized with a plugin, it shouldn't listen selection changes (and doesn't need to notify widgets of selection changes).
MozReview-Commit-ID: FOVFFgA2nOz
--HG--
extra : rebase_source : 3e16d5023835f99f82934e754d2e7db70474f9ee
e1d8dafcd9