Preliminary work on resuming downloads whose connections have expired.

chrome/browser/renderer_host/resource_dispatcher_host.h

Index: chrome/browser/renderer_host/resource_dispatcher_host.h
diff --git a/chrome/browser/renderer_host/resource_dispatcher_host.h b/chrome/browser/renderer_host/resource_dispatcher_host.h
index 18781772eb0de178ae4212e13fadc7cc99f0d3a0..23779f605599bd82cb21c42a1b832d8a261ab93e 100644
--- a/chrome/browser/renderer_host/resource_dispatcher_host.h
+++ b/chrome/browser/renderer_host/resource_dispatcher_host.h
@@ -23,6 +23,7 @@
 #include "base/scoped_ptr.h"
 #include "base/timer.h"
 #include "chrome/common/child_process_info.h"
+#include "chrome/browser/renderer_host/global_request_id.h"
 #include "chrome/browser/renderer_host/resource_queue.h"
 #include "ipc/ipc_message.h"
 #include "net/url_request/url_request.h"
@@ -42,8 +43,8 @@ class SSLClientAuthHandler;
 class UserScriptListener;
 class URLRequestContext;
 class WebKitThread;
+struct DownloadCreateInfo;
 struct DownloadSaveInfo;
-struct GlobalRequestID;
 struct ViewHostMsg_Resource_Request;
 struct ViewMsg_ClosePage_Params;
 
@@ -111,7 +112,8 @@ class ResourceDispatcherHost : public URLRequest::Delegate {
                      bool prompt_for_save_location,
                      int process_unique_id,
                      int route_id,
-                     URLRequestContext* request_context);
+                     URLRequestContext* request_context,
+                     uint64 start_offset);
 
   // Initiates a save file from the browser process (as opposed to a resource
   // request from the renderer or another child process).
@@ -150,11 +152,20 @@ class ResourceDispatcherHost : public URLRequest::Delegate {
   // Pauses or resumes network activity for a particular request.
   void PauseRequest(int process_unique_id, int request_id, bool pause);
 
+  // Restarts network activity for a particular request.
+  void RestartRequest(int process_unique_id,
+                      int request_id,
+                      DownloadCreateInfo* info);
+
   // Returns the number of pending requests. This is designed for the unittests
-  int pending_requests() const {
+  int pending_request_count() const {
     return static_cast<int>(pending_requests_.size());
   }
 
+  int interrupted_request_count() const {
+    return static_cast<int>(interrupted_requests_.size());
+  }
+
   // Intended for unit-tests only. Returns the memory cost of all the
   // outstanding requests (pending and blocked) for |process_unique_id|.
   int GetOutstandingRequestsMemoryCost(int process_unique_id) const;
@@ -246,6 +257,9 @@ class ResourceDispatcherHost : public URLRequest::Delegate {
   void NotifyResponseCompleted(URLRequest* request, int process_unique_id);
 
   void RemovePendingRequest(int process_unique_id, int request_id);
+  void RemoveInterruptedRequest(int process_unique_id, int request_id);
+  void MovePendingRequestToInterrupted(int process_unique_id, int request_id);
+  void MoveInterruptedRequestToPending(int process_unique_id, int request_id);
 
   // Causes all new requests for the route identified by
   // |process_unique_id| and |route_id| to be blocked (not being
@@ -302,6 +316,11 @@ class ResourceDispatcherHost : public URLRequest::Delegate {
   // Resumes the given request by calling OnResponseStarted or OnReadCompleted.
   void ResumeRequest(const GlobalRequestID& request_id);
 
+  // Restarts the given request's download operation.
+  static void RestartDownload(ResourceDispatcherHost* rdh,
+                              const GlobalRequestID& request_id,
+                              DownloadCreateInfo* info);
+
   // Internal function to start reading for the first time.
   void StartReading(URLRequest* request);
 
@@ -351,10 +370,16 @@ class ResourceDispatcherHost : public URLRequest::Delegate {
   // out we have a lot of things here.
   typedef std::map<GlobalRequestID, URLRequest*> PendingRequestList;
 
+  // Accumulates matching requests from the given list.
+  std::vector<GlobalRequestID> GetMatchingRequests(
+      int process_unique_id,
+      int route_id,
+      const PendingRequestList& requests);
+
   // Deletes the pending request identified by the iterator passed in.
   // This function will invalidate the iterator passed in. Callers should
   // not rely on this iterator being valid on return.
-  void RemovePendingRequest(const PendingRequestList::iterator& iter);
+  void RemoveRequestFromMap(const PendingRequestList::iterator& iter);
 
   // Notify our observers that we started receiving a response for a request.
   void NotifyResponseStarted(URLRequest* request, int process_unique_id);
@@ -404,18 +429,25 @@ class ResourceDispatcherHost : public URLRequest::Delegate {
                         const GURL& new_first_party_for_cookies);
 
   ResourceHandler* CreateSafeBrowsingResourceHandler(
-      ResourceHandler* handler, int child_id, int route_id,
+      ResourceHandler* handler, int process_unique_id, int route_id,
       ResourceType::Type resource_type);
 
   // Creates ResourceDispatcherHostRequestInfo for a browser-initiated request
   // (a download or a page save). |download| should be true if the request
   // is a file download.
   ResourceDispatcherHostRequestInfo* CreateRequestInfoForBrowserRequest(
-      ResourceHandler* handler, int child_id, int route_id, bool download);
+      ResourceHandler* handler,
+      int process_unique_id,
+      int route_id,
+      bool download);
 
-  // Returns true if |request| is in |pending_requests_|.
+  // Returns true if |request| is in |pending_requests_| or
+  // |interrupted_requests_|.
   bool IsValidRequest(URLRequest* request);
 
+  // Returns true if |request| is in |interrupted_requests_|.
+  bool IsInterruptedRequest(URLRequest* request);
+
   // Returns true if the message passed in is a resource related message.
   static bool IsResourceDispatcherHostMessage(const IPC::Message&);
 
@@ -432,6 +464,9 @@ class ResourceDispatcherHost : public URLRequest::Delegate {
 
   PendingRequestList pending_requests_;
 
+  // This list contains all the interrupted requests.
+  PendingRequestList interrupted_requests_;
+
   // A timer that periodically calls UpdateLoadStates while pending_requests_
   // is not empty.
   base::RepeatingTimer<ResourceDispatcherHost> update_load_states_timer_;