Gets mash to use WmToplevelWindowEventHandler

mash/wm/drag_window_resizer.h

Index: mash/wm/drag_window_resizer.h
diff --git a/mash/wm/drag_window_resizer.h b/mash/wm/drag_window_resizer.h
new file mode 100644
index 0000000000000000000000000000000000000000..b33723cf639a77260722f4247292edc36e6ff23a
--- /dev/null
+++ b/mash/wm/drag_window_resizer.h
@@ -0,0 +1,38 @@
+// Copyright 2016 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.
+
+#ifndef MASH_WM_DRAG_WINDOW_RESIZER_H_
+#define MASH_WM_DRAG_WINDOW_RESIZER_H_
+
+#include <memory>
+
+#include "ash/wm/common/window_resizer.h"
+#include "base/macros.h"
+
+namespace mash {
+namespace wm {
+
+// DragWindowResizer is a decorator of WindowResizer and adds the ability to
+// drag windows across displays.
+class DragWindowResizer : public ash::WindowResizer {
+ public:
+  DragWindowResizer(std::unique_ptr<WindowResizer> next_window_resizer,
+                    ash::wm::WindowState* window_state);
+  ~DragWindowResizer() override;
+
+  // WindowResizer:
+  void Drag(const gfx::Point& location, int event_flags) override;
+  void CompleteDrag() override;
+  void RevertDrag() override;
+
+ private:
+  std::unique_ptr<ash::WindowResizer> next_window_resizer_;
+
+  DISALLOW_COPY_AND_ASSIGN(DragWindowResizer);
+};
+
+}  // namespace wm
+}  // namespace mash
+
+#endif  // MASH_WM_DRAG_WINDOW_RESIZER_H_