Fix the build; re-add line missed in revert of deleted file.

ui/views/controls/textfield/native_textfield_views_unittest.cc

Index: ui/views/controls/textfield/native_textfield_views_unittest.cc
diff --git a/ui/views/controls/textfield/native_textfield_views_unittest.cc b/ui/views/controls/textfield/native_textfield_views_unittest.cc
index 8fac7f2bbbc01f274959988590e22cae9a56f05c..54f7337d327b76db80a4697d8c2776430166a678 100644
--- a/ui/views/controls/textfield/native_textfield_views_unittest.cc
+++ b/ui/views/controls/textfield/native_textfield_views_unittest.cc
@@ -79,6 +79,8 @@ class TestTextfield : public views::Textfield {
 
   void clear() { key_received_ = key_handled_ = false; }
 
+  bool focusable() const { return View::focusable(); }
+
  private:
   bool key_handled_;
   bool key_received_;