[Downloads] Ask DownloadHistory if a download was from history.

chrome/browser/download/download_service.cc

Index: chrome/browser/download/download_service.cc
diff --git a/chrome/browser/download/download_service.cc b/chrome/browser/download/download_service.cc
index fd87ca02aa2bef88feb72aa3adc2e8247f60a1d4..5d45416bc58357350d5c8200b7bf980f3a6bb9ec 100644
--- a/chrome/browser/download/download_service.cc
+++ b/chrome/browser/download/download_service.cc
@@ -65,9 +65,8 @@ ChromeDownloadManagerDelegate* DownloadService::GetDownloadManagerDelegate() {
 
   // Pass an empty delegate when constructing the DownloadUIController. The
   // default delegate does all the notifications we need.
-  scoped_ptr<DownloadUIController::Delegate> empty_ui_delegate;
-  download_ui_.reset(new DownloadUIController(manager,
-                                              empty_ui_delegate.Pass()));
+  download_ui_.reset(new DownloadUIController(
+      manager, scoped_ptr<DownloadUIController::Delegate>()));
 
   // Include this download manager in the set monitored by the
   // global status updater.