Notify WebContentsObservers of lost webcontents focus on MAC

Seems the mechanism implemented for aura web contents view was
not moved correctly to mac web contents view. This change applies
the needed changes to make web contents observers to be notified
of lost focus on MAC.

This omission on Mac seems to only affect UMA histograms.


Change-Id: I47d8063d3258b9e6c684899f763198b5f9f8ffff
Reviewed-by: Avi Drissman <>
Reviewed-by: Trent Apted <>
Commit-Queue: Trent Apted <>
Cr-Commit-Position: refs/heads/master@{#660312}
2 files changed