Move views::Accelerator to ui in order to use it from aura code.

views/controls/menu/menu_delegate.h

Index: views/controls/menu/menu_delegate.h
diff --git a/views/controls/menu/menu_delegate.h b/views/controls/menu/menu_delegate.h
index fbae89a474b37d052e810997923c2a53fd75e1e6..dc29eb88ff25038048bc75cf4185f7e16af0b369 100644
--- a/views/controls/menu/menu_delegate.h
+++ b/views/controls/menu/menu_delegate.h
@@ -24,6 +24,12 @@ class Font;
 
 }  // namespace gfx
 
+namespace ui {
+
+class Accelerator;
+
+}  // namespace ui
+
 namespace views {
 
 class DropTargetEvent;
@@ -73,7 +79,7 @@ class VIEWS_EXPORT MenuDelegate {
 
   // If there is an accelerator for the menu item with id |id| it is set in
   // |accelerator| and true is returned.
-  virtual bool GetAccelerator(int id, Accelerator* accelerator);
+  virtual bool GetAccelerator(int id, ui::Accelerator* accelerator);
 
   // Shows the context menu with the specified id. This is invoked when the
   // user does the appropriate gesture to show a context menu. The id