Add initial Controller to DownloadService

components/download/internal/client_set.h

Index: components/download/internal/client_set.h
diff --git a/components/download/internal/client_set.h b/components/download/internal/client_set.h
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+++ b/components/download/internal/client_set.h
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+// 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.
+
+#ifndef COMPONENTS_DOWNLOAD_INTERNAL_CLIENT_SET_H_
+#define COMPONENTS_DOWNLOAD_INTERNAL_CLIENT_SET_H_
+
+#include <map>
+#include <memory>
+#include <set>
+
+#include "base/macros.h"
+#include "components/download/public/clients.h"
+
+namespace download {
+
+// Helper class to hold a list of Clients and associates them with their
+// respective DownloadClient identifier.
+class ClientSet {
+ public:
+  explicit ClientSet(std::unique_ptr<DownloadClientMap> clients);
+  virtual ~ClientSet();
+
+  std::set<DownloadClient> GetRegisteredClients() const;
+  Client* GetClient(DownloadClient id) const;
+
+ private:
+  std::unique_ptr<DownloadClientMap> clients_;
+
+  DISALLOW_COPY_AND_ASSIGN(ClientSet);
+};
+
+}  // namespace download
+
+#endif  // COMPONENTS_DOWNLOAD_INTERNAL_CLIENT_SET_H_