views: support disabled color for CTA 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_utils.h"
@@ skipping 274 matching lines @@
 
 void MdTextButton::UpdateColors() {
   ui::NativeTheme::ColorId fg_color_id =
       is_cta_ ? ui::NativeTheme::kColorId_TextOnCallToActionColor
               : ui::NativeTheme::kColorId_ButtonEnabledColor;
 
   ui::NativeTheme* theme = GetNativeTheme();
   if (!explicitly_set_normal_color())
     LabelButton::SetEnabledTextColors(theme->GetSystemColor(fg_color_id));
 
+  // CTA buttons keep their enabled text color; disabled state is conveyed by
+  // shading the background instead.
+  if (is_cta_)
+    SetTextColor(STATE_DISABLED, theme->GetSystemColor(fg_color_id));
+
   SkColor text_color = label()->enabled_color();
   SkColor bg_color =
-      bg_color_override_
-          ? *bg_color_override_
-          : is_cta_
-                ? theme->GetSystemColor(
-                      ui::NativeTheme::kColorId_CallToActionColor)
-                : is_default()
-                      ? color_utils::BlendTowardOppositeLuma(text_color, 0xD8)
-                      : theme->GetSystemColor(
-                            ui::NativeTheme::kColorId_DialogBackground);
+      theme->GetSystemColor(ui::NativeTheme::kColorId_DialogBackground);
 
+  if (bg_color_override_) {
+    bg_color = *bg_color_override_;
+  } else if (is_cta_) {
+    bg_color = theme->GetSystemColor(
+        ui::NativeTheme::kColorId_CallToActionColor);
+    if (state() == STATE_DISABLED)
+      bg_color = color_utils::BlendTowardOppositeLuma(bg_color, 0x61);
+  } else if (is_default()) {
+    bg_color = color_utils::BlendTowardOppositeLuma(text_color, 0xD8);
+  }
+
+  // TODO(ellyjones): Excise this, in favor of a helper function wrapping
+  // |color_utils::AlphaBlend| and a new NativeTheme color constant.
   bg_color = PlatformStyle::BackgroundColorForMdButton(bg_color, state());
 
   const SkAlpha kStrokeOpacity = 0x1A;
   SkColor stroke_color = (is_cta_ || 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