views: refactor away PlatformStyle::BackgroundColorForMdButton

ui/views/style/platform_style_mac.mm

 // 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.
 
 #include "ui/views/style/platform_style.h"
 
 #include "base/memory/ptr_util.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/paint_vector_icon.h"
@@ skipping 78 matching lines @@
 // static
 void PlatformStyle::ApplyLabelButtonTextStyle(
     views::Label* label,
     ButtonColorByState* color_by_state) {
   const ui::NativeTheme* theme = label->GetNativeTheme();
   ButtonColorByState& colors = *color_by_state;
   colors[Button::STATE_PRESSED] =
       theme->GetSystemColor(ui::NativeTheme::kColorId_ButtonHighlightColor);
 }
 
-// static
-SkColor PlatformStyle::BackgroundColorForMdButton(
-    SkColor color,
-    Button::ButtonState state) {
-  // Per Harmony specs: Pressed state on Mac is + #000 at 0.05 alpha.
-  if (state == Button::STATE_PRESSED)
-    return color_utils::AlphaBlend(SK_ColorBLACK, color, 0x08);
-  return color;
-}
-
 }  // namespace views