Move DisplayChangeObserver + tests from ash to ui.

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..12a874216b5fc87903116f2e38a49e2950aad14c 100644
--- a/ui/base/user_activity/user_activity_detector.h
+++ b/ui/base/user_activity/user_activity_detector.h
@@ -33,6 +33,9 @@ class UI_BASE_EXPORT UserActivityDetector : public ui::PlatformEventObserver {
   // Returns the UserActivityDetector instance if one was created.
   static UserActivityDetector* Get();
 
+  // Calls OnDisplayPowerChanging() on instance if one was created.
+  static void OnDisplayPowerChangingStatic();

[sadrul, 2016/11/29 18:24:40]

Do we need 'Static'?

[kylechar, 2016/11/30 22:53:31]

A change in a parent CL has made this unnecessary regardless.

+
   base::TimeTicks last_activity_time() const { return last_activity_time_; }
   std::string last_activity_name() const { return last_activity_name_; }