aura: Add flag to indicate if a drag session is started with touch or mouse.

chrome/browser/download/download_util.cc

Index: chrome/browser/download/download_util.cc
diff --git a/chrome/browser/download/download_util.cc b/chrome/browser/download/download_util.cc
index eae46e9575391525997cfb6dd26b35b14aa2bb2e..3d2dc09983a19c0bc96872de9306260085b92644 100644
--- a/chrome/browser/download/download_util.cc
+++ b/chrome/browser/download/download_util.cc
@@ -393,11 +393,14 @@ void DragDownload(const DownloadItem* download,
     return;
 
   gfx::Point location = gfx::Screen::GetScreenFor(view)->GetCursorScreenPoint();
+  // TODO(varunjain): Properly determine and send DRAG_EVENT_SOURCE below.
   aura::client::GetDragDropClient(root_window)->StartDragAndDrop(
       data,
       root_window,
+      view,
       location,
-      ui::DragDropTypes::DRAG_COPY | ui::DragDropTypes::DRAG_LINK);
+      ui::DragDropTypes::DRAG_COPY | ui::DragDropTypes::DRAG_LINK,
+      ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE);
 #else  // We are on WIN without AURA
   // We cannot use Widget::RunShellDrag on WIN since the |view| is backed by a
   // TabContentsViewWin, not a NativeWidgetWin.