Add initial Controller to DownloadService

components/download/internal/controller.h

Index: components/download/internal/controller.h
diff --git a/components/download/internal/controller.h b/components/download/internal/controller.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_CONTROLLER_H_
+#define COMPONENTS_DOWNLOAD_INTERNAL_CONTROLLER_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "components/download/public/clients.h"
+
+namespace download {
+
+struct DownloadParams;
+struct SchedulingParams;
+struct StartupStatus;
+
+// The core Controller responsible for gluing various DownloadService components
+// together to manage the active downloads.
+class Controller {
+ public:
+  Controller() = default;
+  virtual ~Controller() = default;
+
+  // Initializes the controller.  Initialization may be asynchronous.
+  virtual void Initialize() = 0;
+
+  // Returns the status of Controller.
+  virtual const StartupStatus& GetStartupStatus() = 0;
+
+  // Starts a download with |params|.  See DownloadParams::StartCallback and
+  // DownloadParams::StartResponse for information on how a caller can determine
+  // whether or not the download was successfully accepted and queued.
+  virtual void StartDownload(const DownloadParams& params) = 0;
+
+  // Pauses a download request associated with |guid| if one exists.
+  virtual void PauseDownload(const std::string& guid) = 0;
+
+  // Resumes a download request associated with |guid| if one exists.  The
+  // download request may or may not start downloading at this time, but it will
+  // no longer be blocked by any prior PauseDownload() actions.
+  virtual void ResumeDownload(const std::string& guid) = 0;
+
+  // Cancels a download request associated with |guid| if one exists.
+  virtual void CancelDownload(const std::string& guid) = 0;
+
+  // Changes the SchedulingParams of a download request associated with |guid|
+  // to |params|.
+  virtual void ChangeDownloadCriteria(const std::string& guid,
+                                      const SchedulingParams& params) = 0;
+
+  // Exposes the owner of the download request for |guid| if one exists.
+  // Otherwise returns DownloadClient::INVALID for an unowned entry.
+  virtual DownloadClient GetOwnerOfDownload(const std::string& guid) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(Controller);
+};
+
+}  // namespace download
+
+#endif  // COMPONENTS_DOWNLOAD_INTERNAL_CONTROLLER_H_