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

content/browser/web_contents/web_contents_view_aura.cc

Index: content/browser/web_contents/web_contents_view_aura.cc
diff --git a/content/browser/web_contents/web_contents_view_aura.cc b/content/browser/web_contents/web_contents_view_aura.cc
index 6a03aadc48389d848ba9c9159b6eaf98398b01ae..1cec2e638cce76b6037e5cbbd0d976daa15095e8 100644
--- a/content/browser/web_contents/web_contents_view_aura.cc
+++ b/content/browser/web_contents/web_contents_view_aura.cc
@@ -461,11 +461,13 @@ void WebContentsViewAura::StartDragging(
     // always start from a mouse-event (e.g. a touch or gesture event could
     // initiate the drag). The location information should be carried over from
     // webkit. http://crbug.com/114754
+    // TODO(varunjain): Properly determine and send DRAG_EVENT_SOURCE below.
     gfx::Point location(
         gfx::Screen::GetScreenFor(GetNativeView())->GetCursorScreenPoint());
     MessageLoop::ScopedNestableTaskAllower allow(MessageLoop::current());
     result_op = aura::client::GetDragDropClient(root_window)->StartDragAndDrop(
-        data, root_window, location, ConvertFromWeb(operations));
+        data, root_window, GetContentNativeView(), location,
+        ConvertFromWeb(operations), ui::DragDropTypes::DRAG_EVENT_SOURCE_MOUSE);
   }
 
   // Bail out immediately if the contents view window is gone. Note that it is