ObserverList::HasObserver now takes a const pointer.

sync/sessions/model_type_registry.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 "sync/sessions/model_type_registry.h"
 
 #include "base/bind.h"
 #include "base/observer_list.h"
 #include "base/thread_task_runner_handle.h"
 #include "sync/engine/directory_commit_contributor.h"
@@ skipping 265 matching lines @@
   if (!type_debug_info_observers_.HasObserver(observer))
     type_debug_info_observers_.AddObserver(observer);
 }
 
 void ModelTypeRegistry::UnregisterDirectoryTypeDebugInfoObserver(
     syncer::TypeDebugInfoObserver* observer) {
   type_debug_info_observers_.RemoveObserver(observer);
 }
 
 bool ModelTypeRegistry::HasDirectoryTypeDebugInfoObserver(
-    syncer::TypeDebugInfoObserver* observer) {
+    const syncer::TypeDebugInfoObserver* observer) const {
   return type_debug_info_observers_.HasObserver(observer);
 }
 
 void ModelTypeRegistry::RequestEmitDebugInfo() {
   for (DirectoryTypeDebugInfoEmitterMap::iterator it =
        directory_type_debug_info_emitter_map_.begin();
        it != directory_type_debug_info_emitter_map_.end(); ++it) {
     it->second->EmitCommitCountersUpdate();
     it->second->EmitUpdateCountersUpdate();
     it->second->EmitStatusCountersUpdate();
@@ skipping 57 matching lines @@
   for (ScopedVector<ModelTypeSyncWorkerImpl>::const_iterator it =
            model_type_sync_workers_.begin();
        it != model_type_sync_workers_.end();
        ++it) {
     enabled_off_thread_types.Put((*it)->GetModelType());
   }
   return enabled_off_thread_types;
 }
 
 }  // namespace syncer