[MacViews] Fix Drag and Drop bugs

ui/views/cocoa/drag_drop_client_mac.mm

Index: ui/views/cocoa/drag_drop_client_mac.mm
diff --git a/ui/views/cocoa/drag_drop_client_mac.mm b/ui/views/cocoa/drag_drop_client_mac.mm
index 83b70ed948f4c76c3bf142c87b179bbe698fc525..8b018fd568e609be7c4e07385f1800fe2ac5c111 100644
--- a/ui/views/cocoa/drag_drop_client_mac.mm
+++ b/ui/views/cocoa/drag_drop_client_mac.mm
@@ -132,6 +132,8 @@ NSDragOperation DragDropClientMac::DragUpdate(id<NSDraggingInfo> sender) {
   if (!data_source_.get()) {
     data_source_.reset([[CocoaDragDropDataProvider alloc]
         initWithPasteboard:[sender draggingPasteboard]]);
+    operation_ = ui::DragDropTypes::NSDragOperationToDragOperation(
+        [sender draggingSourceOperationMask]);
   }
 
   drag_operation = drop_helper_.OnDragOver(
@@ -144,6 +146,7 @@ NSDragOperation DragDropClientMac::Drop(id<NSDraggingInfo> sender) {
   int drag_operation = drop_helper_.OnDrop(
       *[data_source_ data], LocationInView([sender draggingLocation]),
       operation_);
+  data_source_.reset();
   return ui::DragDropTypes::DragOperationToNSDragOperation(drag_operation);
 }