Download driver for components/download.

components/download/internal/download_driver.h

Index: components/download/internal/download_driver.h
diff --git a/components/download/internal/download_driver.h b/components/download/internal/download_driver.h
new file mode 100644
index 0000000000000000000000000000000000000000..9e614a5b7791ca3036771988e737b7f103c96d96
--- /dev/null
+++ b/components/download/internal/download_driver.h
@@ -0,0 +1,71 @@
+// 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_DOWNLOAD_DRIVER_H_
+#define COMPONENTS_DOWNLOAD_INTERNAL_DOWNLOAD_DRIVER_H_
+
+#include <string>
+
+namespace base {
+
+class FilePath;
+
+}  // namespace base
+
+namespace download {
+
+struct DownloadParams;
+
+// The interface that includes all the operations to interact with content
+// download functionalities.
+class DownloadDriver {
+ public:
+  // Observer to receive updates from content download library.
+  // The update events for all downloads will pass through, so it's the
+  // observer's responsibility to filter the events it needs to handle.
+  class Observer {
+   public:
+    // Called when the driver finishes initialization.
+    virtual void OnDriverReady() = 0;

[David Trainor- moved to gerrit, 2017/05/15 20:08:15]

We will need a list of (at least) all in progress downloads here.  Should we
just pass that through on the ready call?

[xingliu, 2017/05/17 19:34:52]

I think get the vector of all downloads here is kind of expensive.

Added a find call that returns a DriverEntry. So the service internal code can
just query each entry based on database records.

We can add it if we really need it.

+
+    // Called when any download is created.
+    virtual void OnDownloadCreated(const std::string& guid) = 0;
+
+    // Called when any download is failed.
+    virtual void OnDownloadFailed(const std::string& guid, int reason) = 0;
+
+    // Called when any download is successfully completed.
+    virtual void OnDownloadSucceeded(const std::string& guid,
+                                     const base::FilePath& path,
+                                     uint64_t size) = 0;
+
+    // Called when any download is updated.
+    virtual void OnDownloadUpdated(const std::string& guid,
+                                   uint64_t bytes_downloaded) = 0;
+  };
+
+  // Starts a new download.
+  virtual void Start(const DownloadParams& params) = 0;
+
+  // Cancels an existing download, all data associated with this download should
+  // be removed.
+  virtual void Cancel(const std::string& guid) = 0;
+
+  // Pauses the download.
+  virtual void Pause(const std::string& guid) = 0;
+
+  // Resumes the download
+  virtual void Resume(const std::string& guid) = 0;
+
+  // If the download driver is ready to accept download operation calls.
+  virtual bool IsReady() const = 0;
+
+  // Set the observer to receive download updates. Can set to nullptr to stop
+  // listening to download updates.
+  virtual void SetObserver(Observer* observer) = 0;
+};
+
+}  // namespace download
+
+#endif  // COMPONENTS_DOWNLOAD_INTERNAL_DOWNLOAD_DRIVER_H_