Reapply r50859 with chromeos fixes.

app/menus/menu_model.h

Index: app/menus/menu_model.h
diff --git a/app/menus/menu_model.h b/app/menus/menu_model.h
index 50f2e54ca318ee91ef4dfec7d85e09d7c7f2a002..f14c8b5085fca0716e55faca24d54cfa612ef755 100644
--- a/app/menus/menu_model.h
+++ b/app/menus/menu_model.h
@@ -20,6 +20,7 @@ class Font;
 namespace menus {
 
 class Accelerator;
+class ButtonMenuItemModel;
 
 // An interface implemented by an object that provides the content of a menu.
 class MenuModel {
@@ -32,6 +33,7 @@ class MenuModel {
     TYPE_CHECK,
     TYPE_RADIO,
     TYPE_SEPARATOR,
+    TYPE_BUTTON_ITEM,
     TYPE_SUBMENU
   };
 
@@ -85,6 +87,9 @@ class MenuModel {
   // is an icon, false otherwise.
   virtual bool GetIconAt(int index, SkBitmap* icon) const = 0;
 
+  // Returns the model for a menu item with a line of buttons at |index|.
+  virtual ButtonMenuItemModel* GetButtonMenuItemAt(int index) const = 0;
+
   // Returns the enabled state of the item at the specified index.
   virtual bool IsEnabledAt(int index) const = 0;