Move DisplayChangeObserver + tests from ash to ui.

ui/base/user_activity/user_activity_detector.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/base/user_activity/user_activity_detector.h"
 
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "build/build_config.h"
@@ skipping 53 matching lines @@
   if (platform_event_source)
     platform_event_source->RemovePlatformEventObserver(this);
   g_instance = nullptr;
 }
 
 // static
 UserActivityDetector* UserActivityDetector::Get() {
   return g_instance;
 }
 
+// static
+void UserActivityDetector::OnDisplayPowerChangingStatic() {
+  if (g_instance)
+    g_instance->OnDisplayPowerChanging();
+}
+
 bool UserActivityDetector::HasObserver(
     const UserActivityObserver* observer) const {
   return observers_.HasObserver(observer);
 }
 
 void UserActivityDetector::AddObserver(UserActivityObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void UserActivityDetector::RemoveObserver(UserActivityObserver* observer) {
@@ skipping 39 matching lines @@
       kNotifyIntervalMs) {
     if (VLOG_IS_ON(1))
       VLOG(1) << "Reporting user activity: " << GetEventDebugString(event);
     for (UserActivityObserver& observer : observers_)
       observer.OnUserActivity(event);
     last_observer_notification_time_ = now;
   }
 }
 
 }  // namespace ui