When the user becomes inactive, we have to record events, that are
important to restore the user's document viewport when he becomes
active again.
We currently don't discriminate view events so events with different
view ID are considered as the same event and thus get overwritten.
The effect of this is that only the last cursor or selection of a
different view (different user working on a document) is updated
when the user becomes active again.
With this we discriminate view events and record them per view ID.
When the user becomes active again, we replay them for all views.
Change-Id: I0c6b9209f4d592d88fb23227c4de41084b8cd736
