MacViews: Implement Full Keyboard Access.

ui/views/controls/button/custom_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_CUSTOM_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_CUSTOM_BUTTON_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "ui/events/event_constants.h"
 #include "ui/gfx/animation/animation_delegate.h"
 #include "ui/gfx/animation/throb_animation.h"
 #include "ui/views/animation/ink_drop_state.h"
 #include "ui/views/controls/button/button.h"
 
 namespace views {
 
 class InkDropDelegate;
 
 // A button with custom rendering. The base of ImageButton and LabelButton.
 // Note that this type of button is not focusable by default and will not be
-// part of the focus chain.  Call SetFocusBehavior(FocusBehavior::ALWAYS) to
-// make it part of the focus chain.
+// part of the focus chain, unless in accessibility mode. Call

[tapted, 2016/04/20 06:05:57]

Where's the "unless in accessibility mode" bit triggered? I was expecting to
find an ACCESSIBLE_ONLY somewhere...

[karandeepb, 2016/05/03 02:54:12]

This inherits from Button, which has a
SetFocusBehavior(FocusBehavior::ACCESSIBLE_ONLY); See
https://code.google.com/p/chromium/codesearch#chromium/src/ui/views/controls/...

+// Button::ConfigureDefaultFocus() to make it part of the focus chain.
 class VIEWS_EXPORT CustomButton : public Button, public gfx::AnimationDelegate {
  public:
   // An enum describing the events on which a button should notify its listener.
   enum NotifyAction {
     NOTIFY_ON_PRESS,
     NOTIFY_ON_RELEASE,
   };
 
   // The menu button's class name.
   static const char kViewClassName[];
@@ skipping 169 matching lines @@
   // because it needs to paint to a layer so it can extend beyond the bounds of
   // |this|.
   views::View* md_focus_ring_;
 
   DISALLOW_COPY_AND_ASSIGN(CustomButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_CUSTOM_BUTTON_H_