mus: Forward user activity from window server to detector.

ui/base/user_activity/user_activity_detector.h

Index: ui/base/user_activity/user_activity_detector.h
diff --git a/ui/base/user_activity/user_activity_detector.h b/ui/base/user_activity/user_activity_detector.h
index f2f68897175bac509db84993e54c19348188e66e..dab5bc407a01cda3c712b2c95c43ed7f64fd8fb3 100644
--- a/ui/base/user_activity/user_activity_detector.h
+++ b/ui/base/user_activity/user_activity_detector.h
@@ -45,6 +45,10 @@ class UI_BASE_EXPORT UserActivityDetector : public ui::PlatformEventObserver {
   // Called when displays are about to be turned on or off.
   void OnDisplayPowerChanging();
 
+  // Handles reports of user activity originating from outside of
+  // PlatformEventSource (e.g. the window server).
+  void HandleExternalUserActivity();
+
   // ui::PlatformEventObserver:
   void WillProcessEvent(const PlatformEvent& platform_event) override {}
   void DidProcessEvent(const PlatformEvent& platform_event) override;