Activation: remove old objects after update done

The update on PSUs is one-by-one, after each PSU is updated, notify
ItemUpdater by onUpdateDone() so that the old object for the PSU is
removed.

Tested: With dummy PSU image and update service, verify the old
        objects are removed on Witherspoon.

Change-Id: I212b8cba9570ad96083d362bf57691fdabb4e42f
diff --git a/test/mocked_activation_listener.hpp b/test/mocked_activation_listener.hpp
new file mode 100644
index 0000000..cbef46d
--- /dev/null
+++ b/test/mocked_activation_listener.hpp
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "activation_listener.hpp"
+
+#include <gmock/gmock.h>
+
+class MockedActivationListener : public ActivationListener
+{
+  public:
+    virtual ~MockedActivationListener() = default;
+
+    MOCK_METHOD2(onUpdateDone, void(const std::string& versionId,
+                                    const std::string& psuInventoryPath));
+};