ObserverList::HasObserver now takes a const pointer.

components/invalidation/invalidator_registrar.cc

Index: components/invalidation/invalidator_registrar.cc
diff --git a/components/invalidation/invalidator_registrar.cc b/components/invalidation/invalidator_registrar.cc
index 80cb7f6f02ce38c9183f72d5a6f41ee6b6083c1e..9ee6a94fbdaff6dc14a02c9db2eef4f94e180bec 100644
--- a/components/invalidation/invalidator_registrar.cc
+++ b/components/invalidation/invalidator_registrar.cc
@@ -135,7 +135,7 @@ InvalidatorRegistrar::GetSanitizedHandlersIdsMap() {
 }
 
 bool InvalidatorRegistrar::IsHandlerRegisteredForTest(
-    InvalidationHandler* handler) const {
+    const InvalidationHandler* handler) const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return handlers_.HasObserver(handler);
 }