Added member data to classes to support download resumption.

content/browser/download/download_item.h

Index: content/browser/download/download_item.h
diff --git a/content/browser/download/download_item.h b/content/browser/download/download_item.h
index 3d3b0e7ace3a8b7454f1f7cc31088b3a2c5cc6e7..0cd0fcbc405a5ab4bab12acf9b5cc17207bd51ac 100644
--- a/content/browser/download/download_item.h
+++ b/content/browser/download/download_item.h
@@ -163,8 +163,11 @@ class CONTENT_EXPORT DownloadItem {
   // Called when the user has validated the download of a dangerous file.
   void DangerousDownloadValidated();
 
-  // Received a new chunk of data
-  void Update(int64 bytes_so_far);
+  // Received a new chunk of data.
+  // |bytes_so_far| is the number of bytes received so far.
+  // |partial_hash| is the hash up to this point.  It will be an empty string
+  // if we are not calculating hashes.
+  void Update(int64 bytes_so_far, const std::string& partial_hash);
 
   // Cancel the download operation. We need to distinguish between cancels at
   // exit (DownloadManager destructor) from user interface initiated cancels
@@ -193,8 +196,11 @@ class CONTENT_EXPORT DownloadItem {
 
   // Download operation had an error.
   // |size| is the amount of data received at interruption.
+  // |partial_hash| is the current hash value at interruption.
   // |reason| is the download interrupt reason code that the operation received.
-  void Interrupted(int64 size, InterruptReason reason);
+  void Interrupted(int64 size,
+                   const std::string partial_hash,
+                   InterruptReason reason);
 
   // Deletes the file from disk and removes the download from the views and
   // history.  |user| should be true if this is the result of the user clicking
@@ -313,6 +319,13 @@ class CONTENT_EXPORT DownloadItem {
   void set_opened(bool opened) { opened_ = opened; }
   bool opened() const { return opened_; }
 
+  const std::string& last_modified_time() const { return last_modified_time_; }
+  void set_last_modified_time(const std::string& time) {
+    last_modified_time_ = time;
+  }
+  const std::string& etag() const { return etag_; }
+  void set_etag(const std::string& tag) { etag_ = tag; }

[Randy Smith (Not in Mondays), 2011/11/15 18:45:26]

Under what circumstances are the setters used?  Can we replace them with an
UpdateOnResumption(DownloadCreateInfo)?

[ahendrickson, 2011/11/16 15:41:08]

We need the getters (or an equivalent function) when we resume a download, and
possibly to save to the history DB.

The setters can be removed, as they only need to be set at construction time
(Done).

[Randy Smith (Not in Mondays), 2011/11/16 18:29:27]

So you're not planning to update these values when you do a resumption?  I'm
inclined to think you should--if you restart, they may change, and there's no
reason to disable continuation after restart if the restart happened because of
an etag/last_modified mismatch.  I'd just rather than that update get done in a
function that's targeted at that update, thus my suggestion of
UpdateOnResumption.

[ahendrickson, 2011/11/19 20:18:03]

You're right, and I'll put them back in when they are necessary.

+
   InterruptReason last_reason() const { return last_reason_; }
 
   DownloadPersistentStoreInfo GetPersistentStoreInfo() const;
@@ -357,6 +370,9 @@ class CONTENT_EXPORT DownloadItem {
   // Internal helper for maintaining consistent received and total sizes.
   void UpdateSize(int64 size);
 
+  // Internal helper for keeping track of the hash as we receive data.
+  void UpdateHash(const std::string& partial_hash);

[Randy Smith (Not in Mondays), 2011/11/15 18:45:26]

Given that we worked out in a different comment thread that it's fairly
important for resumption that the hash and size need to be kept in sync, I'd be
more inclined to fold this argument into UpdateSize (maybe change the name to
UpdateSizeAndHash).

[ahendrickson, 2011/11/16 15:41:08]

Done.

+
   // Called when the entire download operation (including renaming etc)
   // is completed.
   void Completed();
@@ -417,42 +433,48 @@ class CONTENT_EXPORT DownloadItem {
   // It's used to construct a suggested filename.
   std::string referrer_charset_;
 
-  // Total bytes expected
+  // Total bytes expected.
   int64 total_bytes_;
 
-  // Current received bytes
+  // Current received bytes.
   int64 received_bytes_;
 
   // Sha256 hash of the content.  This might be empty either because
-  // the download isn't done yet or because the hash isn't needed
+  // the download hasn't started yet or because the hash isn't needed
   // (ChromeDownloadManagerDelegate::GenerateFileHash() returned false).
   std::string hash_;
 
+  // Server's time stamp for the file.
+  std::string last_modified_time_;
+
+  // Server's ETAG for the file.
+  std::string etag_;
+
   // Last reason.
   InterruptReason last_reason_;
 
-  // Start time for calculating remaining time
+  // Start time for calculating remaining time.
   base::TimeTicks start_tick_;
 
-  // The current state of this download
+  // The current state of this download.
   DownloadState state_;
 
-  // The views of this item in the download shelf and download tab
+  // The views of this item in the download shelf and download tab.
   ObserverList<Observer> observers_;
 
-  // Time the download was started
+  // Time the download was started.
   base::Time start_time_;
 
-  // Time the download completed
+  // Time the download completed.
   base::Time end_time_;
 
-  // Our persistent store handle
+  // Our persistent store handle.
   int64 db_handle_;
 
-  // Our owning object
+  // Our owning object.
   DownloadManager* download_manager_;
 
-  // In progress downloads may be paused by the user, we note it here
+  // In progress downloads may be paused by the user, we note it here.
   bool is_paused_;
 
   // A flag for indicating if the download should be opened at completion.