Introduce ui.dll / libui.so for the component build.

ui/base/models/button_menu_item_model.h

Index: ui/base/models/button_menu_item_model.h
===================================================================
--- ui/base/models/button_menu_item_model.h	(revision 92815)
+++ ui/base/models/button_menu_item_model.h	(working copy)
@@ -9,12 +9,13 @@
 #include <vector>
 
 #include "base/string16.h"
+#include "ui/ui_api.h"
 
 namespace ui {
 
 // A model representing the rows of buttons that should be inserted in a button
 // containing menu item.
-class ButtonMenuItemModel {
+class UI_API ButtonMenuItemModel {
  public:
   // Types of buttons.
   enum ButtonType {
@@ -23,7 +24,7 @@
     TYPE_BUTTON_LABEL
   };
 
-  class Delegate {
+  class UI_API Delegate {
    public:
     // Some command ids have labels that change over time.
     virtual bool IsItemForCommandIdDynamic(int command_id) const;