Changes MouseEvent constructor to take changed_button_flags.

ash/drag_drop/drag_drop_tracker.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/drag_drop/drag_drop_tracker.h"
 
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/coordinate_conversion.h"
 #include "ui/aura/client/window_tree_client.h"
@@ skipping 56 matching lines @@
   gfx::Point location_in_screen = event.location();
   ash::wm::ConvertPointToScreen(capture_window_.get(), &location_in_screen);
   gfx::Point target_root_location = event.root_location();
   aura::Window::ConvertPointToTarget(
       capture_window_->GetRootWindow(),
       ash::wm::GetRootWindowAt(location_in_screen),
       &target_root_location);
   return new ui::MouseEvent(event.type(),
                             target_location,
                             target_root_location,
-                            event.flags());
+                            event.flags(),
+                            static_cast<const ui::MouseEvent&>(event).
+                                changed_button_flags());
 }
 
 }  // namespace internal
 }  // namespace ash