MD text buttons - implement focus ring.

ui/views/controls/button/md_text_button.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_CONTROLS_BUTTON_MD_TEXT_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_MD_TEXT_BUTTON_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "ui/views/animation/button_ink_drop_delegate.h"
 #include "ui/views/controls/button/label_button.h"
 
 namespace views {
 
 // A button class that implements the Material Design text button spec.
 class VIEWS_EXPORT MdTextButton : public LabelButton {
  public:
   // Creates a normal STYLE_BUTTON LabelButton in pre-MD, or an MdTextButton
   // in MD mode.
   static LabelButton* CreateStandardButton(ButtonListener* listener,
                                            const base::string16& text);
 
   // LabelButton:
+  void Layout() override;
   SkColor GetInkDropBaseColor() const override;
   void SetText(const base::string16& text) override;
 
+ protected:
+  // LabelButton:
+  void OnFocus() override;
+  void OnBlur() override;
+
  private:
   MdTextButton(ButtonListener* listener);
   ~MdTextButton() override;
 
   ButtonInkDropDelegate ink_drop_delegate_;
 
+  // A child view to draw the focus ring. This is not done via a FocusPainter
+  // because it needs to paint to a layer so it can extend beyond the bounds of
+  // |this|.
+  views::View* focus_ring_;
+
   DISALLOW_COPY_AND_ASSIGN(MdTextButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_MD_TEXT_BUTTON_H_