Add a Model to the download component.

components/download/internal/test_support/mock_model_client.h

Index: components/download/internal/test_support/mock_model_client.h
diff --git a/components/download/internal/test_support/mock_model_client.h b/components/download/internal/test_support/mock_model_client.h
new file mode 100644
index 0000000000000000000000000000000000000000..6604f2ecbc81c31f063a68db388d9368d920de16
--- /dev/null
+++ b/components/download/internal/test_support/mock_model_client.h
@@ -0,0 +1,29 @@
+// Copyright 2017 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 "components/download/internal/model.h"
+
+#include "components/download/internal/entry.h"
+#include "testing/gmock/include/gmock/gmock.h"
+
+#ifndef COMPONENTS_DOWNLOAD_INTERNAL_TEST_SUPPORT_MOCK_MODEL_CLIENT_H_
+#define COMPONENTS_DOWNLOAD_INTERNAL_TEST_SUPPORT_MOCK_MODEL_CLIENT_H_
+
+namespace download {
+
+class MockModelClient : public Model::Client {
+ public:
+  MockModelClient();
+  ~MockModelClient() override;
+
+  // DownloadModel::Client implementation.
+  MOCK_METHOD1(OnInitialized, void(bool));
+  MOCK_METHOD1(OnDestroyed, void(bool));
+  MOCK_METHOD2(OnStoreUpdateFailed, void(DownloadClient, const std::string&));
+  MOCK_METHOD3(OnItemAdded, void(bool, DownloadClient, const std::string&));
+};
+
+}  // namespace download
+
+#endif  // COMPONENTS_DOWNLOAD_INTERNAL_TEST_SUPPORT_MOCK_MODEL_CLIENT_H_