ObserverList::HasObserver now takes a const pointer.

ui/wm/core/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/wm/core/user_activity_detector.h"
 
 #include "base/format_macros.h"
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
 #include "ui/events/event.h"
@@ skipping 31 matching lines @@
 // will be reported as user activity and turn the screen back on; too high
 // and we'll ignore legitimate activity.
 const int UserActivityDetector::kDisplayPowerChangeIgnoreMouseMs = 1000;
 
 UserActivityDetector::UserActivityDetector() {
 }
 
 UserActivityDetector::~UserActivityDetector() {
 }
 
-bool UserActivityDetector::HasObserver(UserActivityObserver* observer) const {
+bool UserActivityDetector::HasObserver(
+    const UserActivityObserver* observer) const {
   return observers_.HasObserver(observer);
 }
 
 void UserActivityDetector::AddObserver(UserActivityObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void UserActivityDetector::RemoveObserver(UserActivityObserver* observer) {
   observers_.RemoveObserver(observer);
 }
@@ skipping 40 matching lines @@
       (now - last_observer_notification_time_).InMillisecondsF() >=
       kNotifyIntervalMs) {
     if (VLOG_IS_ON(1))
       VLOG(1) << "Reporting user activity: " << GetEventDebugString(event);
     FOR_EACH_OBSERVER(UserActivityObserver, observers_, OnUserActivity(event));
     last_observer_notification_time_ = now;
   }
 }
 
 }  // namespace wm