Shift passage of FileStream in downloads system to be by scoped_ptr<>.

content/browser/web_contents/web_drag_source_mac.mm

Index: content/browser/web_contents/web_drag_source_mac.mm
diff --git a/content/browser/web_contents/web_drag_source_mac.mm b/content/browser/web_contents/web_drag_source_mac.mm
index 8cccff57a478d956c2fb7c252b3e432a0671a62a..98712116d2daa1eaef04e01b0b0dbae75d39410f 100644
--- a/content/browser/web_contents/web_drag_source_mac.mm
+++ b/content/browser/web_contents/web_drag_source_mac.mm
@@ -342,16 +342,16 @@ void PromiseWriterHelper(const WebDropData& drop_data,
   // which is blocking.  Since this operation is already blocking the
   // UI thread on OSX, it should be reasonable to let it happen.
   base::ThreadRestrictions::ScopedAllowIO allowIO;
-  FileStream* fileStream =
+  scoped_ptr<FileStream> fileStream(
       drag_download_util::CreateFileStreamForDrop(
-          &filePath, content::GetContentClient()->browser()->GetNetLog());
-  if (!fileStream)
+          &filePath, content::GetContentClient()->browser()->GetNetLog()));
+  if (!fileStream.get())
     return nil;
 
   if (downloadURL_.is_valid()) {
     scoped_refptr<DragDownloadFile> dragFileDownloader(new DragDownloadFile(
         filePath,
-        linked_ptr<net::FileStream>(fileStream),
+        fileStream.Pass(),
         downloadURL_,
         content::Referrer(contents_->GetURL(), dropData_->referrer_policy),
         contents_->GetEncoding(),