downloads: prevent "Clear all" from removing in progress downloads

chrome/browser/ui/webui/downloads_dom_handler.h

Index: chrome/browser/ui/webui/downloads_dom_handler.h
diff --git a/chrome/browser/ui/webui/downloads_dom_handler.h b/chrome/browser/ui/webui/downloads_dom_handler.h
index 1eb1ecb976bd5c68d510476769fcd7187b6a94b2..06890acdcb06079d2493cc3b2056eb980b560c7a 100644
--- a/chrome/browser/ui/webui/downloads_dom_handler.h
+++ b/chrome/browser/ui/webui/downloads_dom_handler.h
@@ -103,6 +103,9 @@ class DownloadsDOMHandler : public content::WebUIMessageHandler,
   // iteration. Protected rather than private for use in tests.
   void ScheduleSendCurrentDownloads();
 
+  // Protected for testing.
+  virtual content::DownloadManager* GetMainNotifierManager();
+
  private:
   // Shorthand for |observing_items_|, which tracks all items that this is
   // observing so that RemoveObserver will be called for all of them.