Make download items drag sources on OS X.

chrome/browser/cocoa/download_item_button.mm

Index: chrome/browser/cocoa/download_item_button.mm
diff --git a/chrome/browser/cocoa/download_item_button.mm b/chrome/browser/cocoa/download_item_button.mm
new file mode 100644
index 0000000000000000000000000000000000000000..41a62c8de35916a2265492cf94da17e680a480e8
--- /dev/null
+++ b/chrome/browser/cocoa/download_item_button.mm
@@ -0,0 +1,21 @@
+// Copyright (c) 2010 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_button.h"
+
+#include "base/sys_string_conversions.h"
+
+@implementation DownloadItemButton
+
+@synthesize download = downloadPath_;
+
+// Overridden from DraggableButton.
+- (void)beginDrag:(NSEvent*)event {
+  if (!downloadPath_.empty()) {
+    NSString* filename = base::SysUTF8ToNSString(downloadPath_.value());
+    [self dragFile:filename fromRect:[self bounds] slideBack:YES event:event];
+  }
+}
+
+@end