[ash] Add TYPE_DIALOG and its item's LauncherContextMenu

ash/shelf/shelf_delegate.h

Index: ash/shelf/shelf_delegate.h
diff --git a/ash/shelf/shelf_delegate.h b/ash/shelf/shelf_delegate.h
index e168c47027707d2a66b57bf58cae755f6d452c4e..57f7321e6207f41bf0666ffb094abf1d171de5e0 100644
--- a/ash/shelf/shelf_delegate.h
+++ b/ash/shelf/shelf_delegate.h
@@ -8,6 +8,10 @@
 #include "ash/ash_export.h"
 #include "ash/launcher/launcher_types.h"
 
+namespace aura {
+class Window;
+}
+
 namespace ash {
 class Launcher;
 
@@ -45,6 +49,11 @@ class ASH_EXPORT ShelfDelegate {
 
   // Unpins app item with |app_id|.
   virtual void UnpinAppWithID(const std::string& app_id) = 0;
+
+  // Returns |true| if the user is allowed to modify the shelf auto-hide
+  // behavior on |root_window|.
+  virtual bool CanUserModifyShelfAutoHideBehavior(
+      aura::Window* root_window) const = 0;
 };
 
 }  // namespace ash