Make download items drag sources on OS X.

chrome/browser/cocoa/download_item_controller.mm

 // Copyright (c) 2009 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.
 
 #import "chrome/browser/cocoa/download_item_controller.h"
 
 #include "app/gfx/text_elider.h"
 #include "app/l10n_util_mac.h"
 #include "app/resource_bundle.h"
 #include "base/mac_util.h"
 #include "base/sys_string_conversions.h"
+#import "chrome/browser/cocoa/download_item_button.h"
 #import "chrome/browser/cocoa/download_item_cell.h"
 #include "chrome/browser/cocoa/download_item_mac.h"
 #import "chrome/browser/cocoa/download_shelf_controller.h"
 #import "chrome/browser/cocoa/ui_localizer.h"
 #include "chrome/browser/download/download_item_model.h"
 #include "chrome/browser/download/download_shelf.h"
 #include "chrome/browser/download/download_util.h"
 #include "grit/generated_resources.h"
 #include "grit/theme_resources.h"
 #import "third_party/GTM/AppKit/GTMTheme.h"
@@ skipping 132 matching lines @@
           downloadModel->download()->original_name(), chromeFont, kTextWidth));
       dangerousWarning = l10n_util::GetNSStringFWithFixup(
           IDS_PROMPT_DANGEROUS_DOWNLOAD, elidedFilename);
       confirmButtonTitle = l10n_util::GetNSStringWithFixup(IDS_SAVE_DOWNLOAD);
     }
     [dangerousDownloadLabel_ setStringValue:dangerousWarning];
     [dangerousDownloadConfirmButton_ setTitle:confirmButtonTitle];
     return;
   }
 
-  // Set the correct popup menu.
-  if (downloadModel->download()->state() == DownloadItem::COMPLETE)
+  // Set correct popup menu. Also, set draggable download on completion.
+  if (downloadModel->download()->state() == DownloadItem::COMPLETE) {
     currentMenu_ = completeDownloadMenu_;
-  else
+    [progressView_ setDownload:downloadModel->download()->full_path()];
+  } else {
     currentMenu_ = activeDownloadMenu_;
+  }
 
   [progressView_ setMenu:currentMenu_];  // for context menu
   [cell_ setStateFromDownload:downloadModel];
 }
 
 - (void)setIcon:(NSImage*)icon {
   [cell_ setImage:icon];
 }
 
 - (void)remove {
@@ skipping 144 matching lines @@
 
 - (IBAction)handleCancel:(id)sender {
   menuBridge_->ExecuteItemCommand(DownloadShelfContextMenuMac::CANCEL);
 }
 
 - (IBAction)handleTogglePause:(id)sender {
   menuBridge_->ExecuteItemCommand(DownloadShelfContextMenuMac::TOGGLE_PAUSE);
 }
 
 @end