Initial CL for Downloads resumption.

content/public/browser/resource_dispatcher_host.h

 // Copyright (c) 2012 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 CONTENT_PUBLIC_BROWSER_RESOURCE_DISPATCHER_HOST_H_
 #define CONTENT_PUBLIC_BROWSER_RESOURCE_DISPATCHER_HOST_H_
 
 #include "base/callback_forward.h"
+#include "content/public/browser/download_id.h"
 #include "net/base/net_errors.h"
 
 namespace net {
 class URLRequest;
 }
 
 namespace content {
 
 class DownloadItem;
 class ResourceContext;
 class ResourceDispatcherHostDelegate;
 struct DownloadSaveInfo;
 
 class CONTENT_EXPORT ResourceDispatcherHost {
  public:
   typedef base::Callback<void(DownloadItem*, net::Error)>
     DownloadStartedCallback;
 
   // Returns the singleton instance of the ResourceDispatcherHost.
   static ResourceDispatcherHost* Get();
 
   // This does not take ownership of the delegate. It is expected that the
   // delegate have a longer lifetime than the ResourceDispatcherHost.
   virtual void SetDelegate(ResourceDispatcherHostDelegate* delegate) = 0;
 
   // Controls whether third-party sub-content can pop-up HTTP basic auth
   // dialog boxes.
   virtual void SetAllowCrossOriginAuthPrompt(bool value) = 0;
 
-  // Initiates a download by explicit request of the renderer, e.g. due to
-  // alt-clicking a link.  If the download is started, |started_callback| will
-  // be called on the UI thread with the DownloadItem; otherwise an error code
-  // will be returned.  |is_content_initiated| is used to indicate that the
-  // request was generated from a web page, and hence may not be as trustworthy
-  // as a browser generated request.
+  // Initiates a download by explicit request of the renderer (e.g. due to
+  // alt-clicking a link) or some other chrome subsystem.
+  // |is_content_initiated| is used to indicate that the request was generated
+  // from a web page, and hence may not be as trustworthy as a browser
+  // generated request.  If |download_id| is invalid, a download id will be
+  // automatically assigned to the request, otherwise the specified download id
+  // will be used.  (Note that this will result in re-use of an existing
+  // download item if the download id was already assigned.)  If the download
+  // is started, |started_callback| will be called on the UI thread with the
+  // DownloadItem; otherwise an error code will be returned.
   virtual net::Error BeginDownload(
       scoped_ptr<net::URLRequest> request,
       bool is_content_initiated,
       ResourceContext* context,
       int child_id,
       int route_id,
       bool prefer_cache,
       scoped_ptr<DownloadSaveInfo> save_info,
+      content::DownloadId download_id,
       const DownloadStartedCallback& started_callback) = 0;
 
   // Clears the ResourceDispatcherHostLoginDelegate associated with the request.
   virtual void ClearLoginDelegateForRequest(net::URLRequest* request) = 0;
 
   // Causes all new requests for the route identified by |child_id| and
   // |route_id| to be blocked (not being started) until
   // ResumeBlockedRequestsForRoute is called.
   virtual void BlockRequestsForRoute(int child_id, int route_id) = 0;
 
   // Resumes any blocked request for the specified route id.
   virtual void ResumeBlockedRequestsForRoute(int child_id, int route_id) = 0;
 
  protected:
   virtual ~ResourceDispatcherHost() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_RESOURCE_DISPATCHER_HOST_H_