Have uses of MockImageResourceClient leak less.

Source/core/fetch/MockImageResourceClient.cpp

+// Copyright 2015 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 "config.h"
+#include "core/fetch/MockImageResourceClient.h"
+
+#include "core/fetch/ImageResource.h"
+#include "core/fetch/ResourcePtr.h"
+
+#include <gtest/gtest.h>
+
+namespace blink {
+
+MockImageResourceClient::MockImageResourceClient(const ResourcePtr<Resource>& resource)
+    : m_resource(resource.get())
+    , m_imageChangedCount(0)
+    , m_notifyFinishedCalled(false)
+{
+    m_resource->addClient(this);
+}
+
+MockImageResourceClient::~MockImageResourceClient()
+{
+    if (m_resource)
+        m_resource->removeClient(this);
+}
+
+void MockImageResourceClient::notifyFinished(Resource*)
+{
+    ASSERT_FALSE(m_notifyFinishedCalled);
+    m_notifyFinishedCalled = true;
+}
+
+void MockImageResourceClient::removeAsClient()
+{
+    m_resource->removeClient(this);
+    m_resource = nullptr;
+}
+
+} // namespace blink