Give up focus if the focused view becomes unfocusable

ui/views/controls/button/image_button.h

 // Copyright (c) 2012 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_CONTROLS_BUTTON_IMAGE_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_IMAGE_BUTTON_H_
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/base/layout.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/views/controls/button/custom_button.h"
 
 namespace views {
 
 class Painter;
 
 // An image button.
 
 // Note that this type of button is not focusable by default and will not be
-// part of the focus chain.  Call set_focusable(true) to make it part of the
+// part of the focus chain.  Call SetFocusable(true) to make it part of the
 // focus chain.
 
 class VIEWS_EXPORT ImageButton : public CustomButton {
  public:
   static const char kViewClassName[];
 
   enum HorizontalAlignment {
     ALIGN_LEFT = 0,
     ALIGN_CENTER,
     ALIGN_RIGHT
@@ skipping 137 matching lines @@
   // The parent class's tooltip_text_ is displayed when not toggled, and
   // this one is shown when toggled.
   string16 toggled_tooltip_text_;
 
   DISALLOW_COPY_AND_ASSIGN(ToggleImageButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_IMAGE_BUTTON_H_