views: use darker stroke for non-prominent buttons

ui/views/controls/button/md_text_button.cc

 // 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/controls/button/md_text_button.h"
 
 #include "base/i18n/case_conversion.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/color_palette.h"
@@ skipping 253 matching lines @@
           bg_color, gfx::kDisabledControlAlpha);
   }
 
   if (state() == STATE_PRESSED) {
     SkColor shade =
         theme->GetSystemColor(ui::NativeTheme::kColorId_ButtonPressedShade);
     bg_color = color_utils::GetResultingPaintColor(shade, bg_color);
   }
 
   SkColor stroke_color =
-      is_prominent_ ? SK_ColorTRANSPARENT : SkColorSetA(text_color, 0x33);
+      is_prominent_ ? SK_ColorTRANSPARENT : SkColorSetA(text_color, 0x4e);

[Evan Stade, 2016/10/12 15:28:35]

perhaps a note about how this was calculated or what it means? Something like:

// The spec specifies black with 0x33 alpha for the default stroke. Here we
derive it from the text color: 0x4e with ChromeIconGrey is very close.

[Elly Fong-Jones, 2016/10/12 17:46:46]

Done.

   DCHECK_EQ(SK_AlphaOPAQUE, static_cast<int>(SkColorGetA(bg_color)));
   set_background(Background::CreateBackgroundPainter(
       true, Painter::CreateRoundRectWith1PxBorderPainter(
                 bg_color, stroke_color, kInkDropSmallCornerRadius)));
 }
 
 }  // namespace views