Implemented prototype for new ink drop specs.

chrome/browser/ui/views/toolbar/back_button.h

 // Copyright 2013 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 CHROME_BROWSER_UI_VIEWS_TOOLBAR_BACK_BUTTON_H_
 #define CHROME_BROWSER_UI_VIEWS_TOOLBAR_BACK_BUTTON_H_
 
 #include "chrome/browser/ui/views/toolbar/toolbar_button.h"
 
 namespace ui {
@@ skipping 13 matching lines @@
  public:
   // Takes ownership of the |model|, which can be null if no menu
   // is to be shown.
   BackButton(views::ButtonListener* listener, ui::MenuModel* model);
   ~BackButton() override;
 
   void SetLeadingMargin(int margin);
 
  protected:
   // ToolbarButton:
-  void LayoutInkDrop() override;
+  gfx::Point CalculateInkDropCenter() const override;
 
  private:
   // ToolbarButton:
   const char* GetClassName() const override;
   scoped_ptr<views::LabelButtonBorder> CreateDefaultBorder() const override;
   gfx::Rect GetThemePaintRect() const override;
 
   // Any leading margin to be applied. Used when the back button is in
   // a maximized state to extend to the full window width.
   int margin_leading_;
 
   DISALLOW_COPY_AND_ASSIGN(BackButton);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_TOOLBAR_BACK_BUTTON_H_