Implemented ExternalData interface on DownloadItem and used it for SafeBrowsing.

content/browser/download/download_item.h

 // Copyright (c) 2011 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.
 //
 // Each download is represented by a DownloadItem, and all DownloadItems
 // are owned by the DownloadManager which maintains a global list of all
 // downloads. DownloadItems are created when a user initiates a download,
 // and exist for the duration of the browser life time.
 //
 // Download observers:
 //   DownloadItem::Observer:
 //     - allows observers to receive notifications about one download from start
 //       to completion
 // Use AddObserver() / RemoveObserver() on the appropriate download object to
 // receive state updates.
 
 #ifndef CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_H_
 #pragma once
 
+#include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "base/time.h"
 #include "content/browser/download/download_id.h"
 #include "content/browser/download/download_request_handle.h"
 #include "content/browser/download/download_state_info.h"
@@ skipping 79 matching lines @@
    public:
     virtual void OnDownloadUpdated(DownloadItem* download) = 0;
 
     // Called when a downloaded file has been opened.
     virtual void OnDownloadOpened(DownloadItem* download) = 0;
 
    protected:
     virtual ~Observer() {}
   };
 
+  // Interface for data that can be stored associated with (and owned
+  // by) an object of this class via GetExternalData/SetExternalData.
+  class ExternalData {
+   public:
+    virtual ~ExternalData() {};
+  };
+
   // Constructing from persistent store:
   DownloadItem(DownloadManager* download_manager,
                const DownloadPersistentStoreInfo& info);
 
   // Constructing for a regular download.
   // Takes ownership of the object pointed to by |request_handle|.
   DownloadItem(DownloadManager* download_manager,
                const DownloadCreateInfo& info,
                DownloadRequestHandleInterface* request_handle,
                bool is_otr);
@@ skipping 212 matching lines @@
   // DownloadItem::Cancel/Interrupt; it isn't now because we can't
   // call those functions from
   // DownloadManager::FileSelectionCancelled() without doing some
   // rewrites of the DownloadManager queues.
   void OffThreadCancel(DownloadFileManager* file_manager);
 
   std::string DebugString(bool verbose) const;
 
   void MockDownloadOpenForTesting() { open_enabled_ = false; }
 
+  // Manage data owned by other subsystems associated with the
+  // DownloadItem.  By custom, key is the address of a
+  // static char subsystem_specific_string[] = ".."; defined
+  // in the subsystem, but the only requirement of this interface
+  // is that the key be unique over all data stored with this
+  // DownloadItem.
+  //
+  // Note that SetExternalData takes ownership of the
+  // passed object; it will be destroyed when the DownloadItem is.
+  // If an object is already held by the DownloadItem associated with
+  // the passed key, it will be destroyed on overwrite.
+  ExternalData* GetExternalData(void* key);
+  void SetExternalData(void* key, ExternalData* data);
+
  private:
   // Construction common to all constructors. |active| should be true for new
   // downloads and false for downloads from the history.
   void Init(bool active);
 
   // Internal helper for maintaining consistent received and total sizes.
   void UpdateSize(int64 size);
 
   // Called when the entire download operation (including renaming etc)
   // is completed.
@@ skipping 123 matching lines @@
   // be treated as though the user opened it.
   bool opened_;
 
   // Do we actual open downloads when requested?  For testing purposes
   // only.
   bool open_enabled_;
 
   // Did the delegate delay calling Complete on this download?
   bool delegate_delayed_complete_;
 
+  // External Data storage.  All objects in the store
+  // are owned by the DownloadItem.
+  std::map<void*, ExternalData*> external_data_map_;

[asanka, 2011/11/16 03:52:19]

Would a std::map<const void*, ExternalData*> be better?

[Randy Smith (Not in Mondays), 2011/11/18 02:02:57]

Done.

+
   DISALLOW_COPY_AND_ASSIGN(DownloadItem);
 };
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_ITEM_H_