Add the download component and initial setup

components/download/public/download_params.cc

Index: components/download/public/download_params.cc
diff --git a/components/download/public/download_params.cc b/components/download/public/download_params.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c29da0300d2babd3577270b4c2bd351ca2342c52
--- /dev/null
+++ b/components/download/public/download_params.cc
@@ -0,0 +1,22 @@
+// 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/public/download_params.h"
+
+#include "components/download/public/clients.h"
+
+namespace download {
+
+SchedulingParams::SchedulingParams()
+    : priority(DEFAULT),
+      network_requirements(NONE),
+      battery_requirements(BATTERY_INSENSITIVE) {}
+
+RequestParams::RequestParams() : method("GET") {}
+
+DownloadParams::DownloadParams() : client(INVALID) {}
+
+DownloadParams::~DownloadParams() = default;
+
+}  // namespace download