Makes ash/mus use RootWindowControllerCommon

ash/common/root_window_controller_common.h

 // 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 ASH_COMMON_ROOT_WINDOW_CONTROLLER_COMMON_H_
 #define ASH_COMMON_ROOT_WINDOW_CONTROLLER_COMMON_H_
 
+#include "ash/ash_export.h"
 #include "base/macros.h"
 
 namespace ash {
 namespace wm {
 class RootWindowLayoutManager;
 class WmWindow;
 }
 
 // This will eventually become what is RootWindowController. During the
 // transition it contains code used by both the aura and mus implementations.
 // It should *not* contain any aura specific code.
-class RootWindowControllerCommon {
+class ASH_EXPORT RootWindowControllerCommon {
  public:
   explicit RootWindowControllerCommon(wm::WmWindow* root);
   ~RootWindowControllerCommon();
 
   // Creates the containers (WmWindows) used by the shell.
   void CreateContainers();
 
   // Creates the LayoutManagers for the windows created by CreateContainers().
   void CreateLayoutManagers();
 
   wm::RootWindowLayoutManager* root_window_layout() {
     return root_window_layout_;
   }
 
  private:
   wm::WmWindow* root_;
 
   wm::RootWindowLayoutManager* root_window_layout_;
 
   DISALLOW_COPY_AND_ASSIGN(RootWindowControllerCommon);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_ROOT_WINDOW_CONTROLLER_COMMON_H_