Improve a11y state for ToggleButton.

ui/views/controls/button/toggle_button.h

 // Copyright 2016 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_TOGGLE_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_TOGGLE_BUTTON_H_
 
 #include "ui/gfx/animation/slide_animation.h"
 #include "ui/views/controls/button/custom_button.h"
 
@@ skipping 24 matching lines @@
 
   SkColor GetTrackColor(bool is_on) const;
 
   // CustomButton:
   gfx::Size GetPreferredSize() const override;
   const char* GetClassName() const override;
   void OnPaint(gfx::Canvas* canvas) override;
   void NotifyClick(const ui::Event& event) override;
   void OnBoundsChanged(const gfx::Rect& previous_bounds) override;
   void OnNativeThemeChanged(const ui::NativeTheme* theme) override;
+  void GetAccessibleNodeData(ui::AXNodeData* node_data) override;
   void AddInkDropLayer(ui::Layer* ink_drop_layer) override;
   void RemoveInkDropLayer(ui::Layer* ink_drop_layer) override;
   std::unique_ptr<InkDropRipple> CreateInkDropRipple() const override;
   SkColor GetInkDropBaseColor() const override;
   bool ShouldShowInkDropHighlight() const override;
 
   // gfx::AnimationDelegate:
   void AnimationProgressed(const gfx::Animation* animation) override;
 
   bool is_on_;
   gfx::SlideAnimation slide_animation_;
   ThumbView* thumb_view_;
 
   DISALLOW_COPY_AND_ASSIGN(ToggleButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_TOGGLE_BUTTON_H_