ObserverList::HasObserver now takes a const pointer.

components/invalidation/invalidation_logger.h

 // 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.
 
 #ifndef COMPONENTS_INVALIDATION_INVALIDATION_LOGGER_H_
 #define COMPONENTS_INVALIDATION_INVALIDATION_LOGGER_H_
 
 #include <map>
 #include <set>
 
@@ skipping 42 matching lines @@
   void OnDebugMessage(const base::DictionaryValue& details);
   void OnInvalidation(const syncer::ObjectIdInvalidationMap& details);
 
   // Triggers messages to be sent to the Observers to provide them with
   // the current state of the logging.
   void EmitContent();
 
   // Add and remove observers listening for messages.
   void RegisterObserver(InvalidationLoggerObserver* debug_observer);
   void UnregisterObserver(InvalidationLoggerObserver* debug_observer);
-  bool IsObserverRegistered(InvalidationLoggerObserver* debug_observer);
+  bool IsObserverRegistered(
+      const InvalidationLoggerObserver* debug_observer) const;
 
  private:
   // Send to every Observer a OnStateChange event with the latest state.
   void EmitState();
 
   // Send to every Observer many OnUpdateIds events, each with one registrar
   // and every objectId it currently has registered.
   void EmitUpdatedIds();
 
   // Send to every Observer a vector with the all the current registered
@@ skipping 18 matching lines @@
   // necessarily the same as the keys of latest_ids_, because they might
   // have not registered any object id).
   std::multiset<std::string> registered_handlers_;
 
   DISALLOW_COPY_AND_ASSIGN(InvalidationLogger);
 };
 
 }  // namespace invalidation
 
 #endif  // COMPONENTS_INVALIDATION_INVALIDATION_LOGGER_H_