ObserverList::HasObserver now takes a const pointer.

ui/views/widget/widget.cc

 // Copyright (c) 2012 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/views/widget/widget.h"
 
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 375 matching lines @@
 }
 
 void Widget::AddObserver(WidgetObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void Widget::RemoveObserver(WidgetObserver* observer) {
   observers_.RemoveObserver(observer);
 }
 
-bool Widget::HasObserver(WidgetObserver* observer) {
+bool Widget::HasObserver(const WidgetObserver* observer) const {
   return observers_.HasObserver(observer);
 }
 
 void Widget::AddRemovalsObserver(WidgetRemovalsObserver* observer) {
   removals_observers_.AddObserver(observer);
 }
 
 void Widget::RemoveRemovalsObserver(WidgetRemovalsObserver* observer) {
   removals_observers_.RemoveObserver(observer);
 }
 
-bool Widget::HasRemovalsObserver(WidgetRemovalsObserver* observer) {
+bool Widget::HasRemovalsObserver(const WidgetRemovalsObserver* observer) const {
   return removals_observers_.HasObserver(observer);
 }
 
 bool Widget::GetAccelerator(int cmd_id, ui::Accelerator* accelerator) const {
   return false;
 }
 
 void Widget::ViewHierarchyChanged(
     const View::ViewHierarchyChangedDetails& details) {
   if (!details.is_add) {
@@ skipping 1098 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // internal::NativeWidgetPrivate, NativeWidget implementation:
 
 internal::NativeWidgetPrivate* NativeWidgetPrivate::AsNativeWidgetPrivate() {
   return this;
 }
 
 }  // namespace internal
 }  // namespace views