ObserverList::HasObserver now takes a const pointer.

chromeos/dbus/fake_session_manager_client.cc

Index: chromeos/dbus/fake_session_manager_client.cc
diff --git a/chromeos/dbus/fake_session_manager_client.cc b/chromeos/dbus/fake_session_manager_client.cc
index c5fe549335d4a82ba440673a7cbf24de24db2a48..fab7c3c715b70d2f7845ec1d4bf04e136dd5645c 100644
--- a/chromeos/dbus/fake_session_manager_client.cc
+++ b/chromeos/dbus/fake_session_manager_client.cc
@@ -35,7 +35,7 @@ void FakeSessionManagerClient::RemoveObserver(Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
-bool FakeSessionManagerClient::HasObserver(Observer* observer) {
+bool FakeSessionManagerClient::HasObserver(const Observer* observer) const {
   return observers_.HasObserver(observer);
 }