Downloads: replace BrowserThread::FILE with task scheduler.

content/browser/download/save_package.h

Index: content/browser/download/save_package.h
diff --git a/content/browser/download/save_package.h b/content/browser/download/save_package.h
index 7a4fb8ce2fa85f0ec92a2eb35233b08d8ed75009..b7a8ab93b8eee63fdd89715f1551c870eaa29b40 100644
--- a/content/browser/download/save_package.h
+++ b/content/browser/download/save_package.h
@@ -100,7 +100,7 @@ class CONTENT_EXPORT SavePackage
 
   void Finish();
 
-  // Notifications sent from the FILE thread to the UI thread.
+  // Notifications sent from the download sequence to the UI thread.
   void StartSave(const SaveFileCreateInfo* info);
   bool UpdateSaveProgress(SaveItemId save_item_id,
                           int64_t size,
@@ -386,7 +386,7 @@ class CONTENT_EXPORT SavePackage
   // Map of all saving job which are successfully saved.
   SaveItemIdMap saved_success_items_;
 
-  // Non-owning pointer for handling file writing on the FILE thread.
+  // Non-owning pointer for handling file writing on the download sequence.
   SaveFileManager* file_manager_ = nullptr;
 
   // DownloadManager owns the DownloadItem and handles history and UI.