Add MenuModelAdapter to wrap ui::MenuModel with views::MenuDelegate interface.

views/views_delegate.h

Index: views/views_delegate.h
diff --git a/views/views_delegate.h b/views/views_delegate.h
index 9df7327b99232e3cea6d31499c897c8f87dfc310..417c33452a6a44cec2a08d8ac485cb0813858897 100644
--- a/views/views_delegate.h
+++ b/views/views_delegate.h
@@ -80,6 +80,9 @@ class ViewsDelegate {
   virtual void AddRef() = 0;
   virtual void ReleaseRef() = 0;
 
+  // Converts views::Event::flags to a WindowOpenDisposition.
+  virtual int GetDispositionForEvent(int event_flags) = 0;
+
   // The active ViewsDelegate used by the views system.
   static ViewsDelegate* views_delegate;
 };