Preliminary work on resuming downloads whose connections have expired.

chrome/browser/download/download_item.h

Index: chrome/browser/download/download_item.h
diff --git a/chrome/browser/download/download_item.h b/chrome/browser/download/download_item.h
index 3431bc7976fc57c74e1fc26620a57b3dbd26f758..d3660ed58caddfcb9be9f844439407af0b41752d 100644
--- a/chrome/browser/download/download_item.h
+++ b/chrome/browser/download/download_item.h
@@ -39,7 +39,8 @@ class DownloadItem {
     IN_PROGRESS,
     COMPLETE,
     CANCELLED,
-    REMOVING
+    REMOVING,
+    INTERRUPTED
   };
 
   enum SafetyState {
@@ -60,6 +61,9 @@ class DownloadItem {
     // Called when a downloaded file has been opened.
     virtual void OnDownloadOpened(DownloadItem* download) = 0;
 
+    // Called when a downloaded file has been interrupted (had an error).
+    virtual void OnDownloadInterrupted(DownloadItem* download) = 0;
+
    protected:
     virtual ~Observer() {}
   };
@@ -132,6 +136,15 @@ class DownloadItem {
   // is finished.
   void Finished();
 
+  // Download operation had an error.
+  // |size| is the amount of data received so far, and |os_error| is the error
+  // code that the operation received.
+  void Interrupted(int64 size, int os_error);
+
+  // User has resumed a download after an interruption.
+  // |new_request_id| is the new request ID associated with the download.
+  void Resumed(int new_request_id);
+
   // The user wants to remove the download from the views and history. If
   // |delete_file| is true, the file is deleted on the disk.
   void Remove(bool delete_file);
@@ -162,6 +175,9 @@ class DownloadItem {
   // Returns true if this item matches |query|. |query| must be lower-cased.
   bool MatchesQuery(const string16& query) const;
 
+  bool IsPartialDownload() const;
+  bool IsInterruptedDownload() const;
+
   // Accessors
   DownloadState state() const { return state_; }
   FilePath full_path() const { return full_path_; }
@@ -173,6 +189,7 @@ class DownloadItem {
   int64 total_bytes() const { return total_bytes_; }
   void set_total_bytes(int64 total_bytes) { total_bytes_ = total_bytes; }
   int64 received_bytes() const { return received_bytes_; }
+  int last_os_error() const { return last_os_error_; }
   int32 id() const { return id_; }
   base::Time start_time() const { return start_time_; }
   void set_db_handle(int64 handle) { db_handle_ = handle; }
@@ -247,6 +264,9 @@ class DownloadItem {
   // Current received bytes
   int64 received_bytes_;
 
+  // Last error.
+  int last_os_error_;
+
   // Start time for calculating remaining time
   base::TimeTicks start_tick_;