ObserverList::HasObserver now takes a const pointer.

components/invalidation/invalidation_logger.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 "components/invalidation/invalidation_logger.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
 #include "components/invalidation/invalidation_handler.h"
 #include "components/invalidation/invalidation_logger_observer.h"
@@ skipping 98 matching lines @@
     InvalidationLoggerObserver* debug_observer) {
   observer_list_.AddObserver(debug_observer);
 }
 
 void InvalidationLogger::UnregisterObserver(
     InvalidationLoggerObserver* debug_observer) {
   observer_list_.RemoveObserver(debug_observer);
 }
 
 bool InvalidationLogger::IsObserverRegistered(
-    InvalidationLoggerObserver* debug_observer) {
+    const InvalidationLoggerObserver* debug_observer) const {
   return observer_list_.HasObserver(debug_observer);
 }
 }  // namespace invalidation