Moves WorkspaceEventHandler to ash/common

ash/wm/workspace/workspace_event_handler_test_helper.h

-// 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.
-
-#ifndef ASH_WM_WORKSPACE_WORKSPACE_EVENT_HANDLER_TEST_HELPER_H_
-#define ASH_WM_WORKSPACE_WORKSPACE_EVENT_HANDLER_TEST_HELPER_H_
-
-#include "ash/wm/workspace/workspace_event_handler.h"
-
-#include "base/macros.h"
-
-namespace ash {
-
-class WorkspaceEventHandlerTestHelper {
- public:
-  explicit WorkspaceEventHandlerTestHelper(WorkspaceEventHandler* handler);
-  ~WorkspaceEventHandlerTestHelper();
-
-  MultiWindowResizeController* resize_controller() {
-    return &(handler_->multi_window_resize_controller_);
-  }
-
- private:
-  WorkspaceEventHandler* handler_;
-
-  DISALLOW_COPY_AND_ASSIGN(WorkspaceEventHandlerTestHelper);
-};
-
-}  // namespace ash
-
-#endif  // ASH_WM_WORKSPACE_WORKSPACE_EVENT_HANDLER_TEST_HELPER_H_