views: provide feedback when editing fails

ui/views/style/platform_style.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_VIEWS_STYLE_PLATFORM_STYLE_H_
 #define UI_VIEWS_STYLE_PLATFORM_STYLE_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 74 matching lines @@
   // Applies platform styles to |label| and fills |color_by_state| with the text
   // colors for normal, pressed, hovered, and disabled states, if the colors for
   // Button::STYLE_BUTTON buttons differ from those provided by ui::NativeTheme.
   static void ApplyLabelButtonTextStyle(Label* label,
                                         ButtonColorByState* color_by_state);
 
   // Applies the current system theme to the default border created by |button|.
   static std::unique_ptr<Border> CreateThemedLabelButtonBorder(
       LabelButton* button);
 
+  // Called whenever a textfield keypress is unhandled for any reason. Gives
+  // visual/audio feedback about the unhandled key if platform-appropriate.
+  static void OnTextfieldKeypressUnhandled();
+
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PlatformStyle);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_STYLE_PLATFORM_STYLE_H_