Change ordering of Shell event handlers:

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index b9aa55e4a581196a2da4d17ea321c53204157c5e..76b4638854bcab6404527e32d9abed9bade6ac70 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -537,14 +537,14 @@ void Shell::Init() {
       lock_state_controller_.get()));
   AddShellObserver(lock_state_controller_.get());
 
+  drag_drop_controller_.reset(new internal::DragDropController);
   mouse_cursor_filter_.reset(new internal::MouseCursorEventFilter());
-  AddPreTargetHandler(mouse_cursor_filter_.get());
+  PrependPreTargetHandler(mouse_cursor_filter_.get());
 
   // Create Controllers that may need root window.
   // TODO(oshima): Move as many controllers before creating
   // RootWindowController as possible.
   visibility_controller_.reset(new AshVisibilityController);
-  drag_drop_controller_.reset(new internal::DragDropController);
   user_action_client_.reset(delegate_->CreateUserActionClient());
   window_modality_controller_.reset(
       new views::corewm::WindowModalityController);