Componentize component_updater: Split content::ResourceThrottle from CUS.

chrome/browser/component_updater/component_updater_resource_throttle.h

+// Copyright 2014 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 CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_RESOURCE_THROTTLE_H_
+#define CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_RESOURCE_THROTTLE_H_
+
+#include <string>
+
+namespace content {
+class ResourceThrottle;
+}
+
+namespace component_updater {
+
+class ComponentUpdateService;
+
+// Returns a network resource throttle. It means that a component will be
+// downloaded and installed before the resource is unthrottled. This function
+// can be called from the IO thread.
+content::ResourceThrottle* GetOnDemandResourceThrottle(
+    ComponentUpdateService* cus,
+    const std::string& crx_id);
+
+}  // namespace component_updater
+
+#endif  // CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_RESOURCE_THROTTLE_H_