views: fix MdTextButton stroke alpha

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 246 matching lines @@
       bg_color = color_utils::BlendTowardOppositeLuma(
           bg_color, gfx::kDisabledControlAlpha);
   }
 
   if (state() == STATE_PRESSED) {
     SkColor shade =
         theme->GetSystemColor(ui::NativeTheme::kColorId_ButtonPressedShade);
     bg_color = color_utils::GetResultingPaintColor(shade, bg_color);
   }
 
-  const SkAlpha kStrokeOpacity = 0x1A;
-  SkColor stroke_color = (is_prominent_ || color_utils::IsDark(text_color))
+  // Prominent buttons have no outside stroke at all. Fake it by using zero
+  // opacity so the code below can still use
+  // CreateRoundRectWith1PxBorderPainter().
+  const SkAlpha kStrokeOpacity = is_prominent_ ? 0x00 : 0x33;
+  SkColor stroke_color = color_utils::IsDark(text_color)
                              ? SkColorSetA(SK_ColorBLACK, kStrokeOpacity)
                              : SkColorSetA(SK_ColorWHITE, 2 * kStrokeOpacity);
 
   DCHECK_EQ(SK_AlphaOPAQUE, static_cast<int>(SkColorGetA(bg_color)));
   set_background(Background::CreateBackgroundPainter(
       true, Painter::CreateRoundRectWith1PxBorderPainter(
                 bg_color, stroke_color, kInkDropSmallCornerRadius)));
 }
 
 }  // namespace views