Update dialog button text color for Harmony per the latest button spec

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 "base/memory/ptr_util.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/gfx/canvas.h"
@@ skipping 220 matching lines @@
 
   // TODO(estade): can we get rid of the platform style border hoopla if
   // we apply the MD treatment to all buttons, even GTK buttons?
   const int horizontal_padding = LayoutProvider::Get()->GetDistanceMetric(
       DISTANCE_BUTTON_HORIZONTAL_PADDING);
   SetBorder(CreateEmptyBorder(top_padding, horizontal_padding, bottom_padding,
                               horizontal_padding));
 }
 
 void MdTextButton::UpdateColors() {
-  ui::NativeTheme::ColorId fg_color_id =
-      is_prominent_ ? ui::NativeTheme::kColorId_TextOnProminentButtonColor
-                    : ui::NativeTheme::kColorId_ButtonEnabledColor;
-
   ui::NativeTheme* theme = GetNativeTheme();
+  SkColor enabled_text_color = style::GetColor(
+      label()->text_context(),
+      is_prominent_ ? style::STYLE_DIALOG_BUTTON_DEFAULT : style::STYLE_PRIMARY,
+      theme);
   if (!explicitly_set_normal_color()) {
     const auto colors = explicitly_set_colors();
-    LabelButton::SetEnabledTextColors(theme->GetSystemColor(fg_color_id));
+    LabelButton::SetEnabledTextColors(enabled_text_color);
     set_explicitly_set_colors(colors);
   }
 
   // Prominent buttons keep their enabled text color; disabled state is conveyed
   // by shading the background instead.
   if (is_prominent_)
-    SetTextColor(STATE_DISABLED, theme->GetSystemColor(fg_color_id));
+    SetTextColor(STATE_DISABLED, enabled_text_color);
 
   SkColor text_color = label()->enabled_color();
   SkColor bg_color =
       theme->GetSystemColor(ui::NativeTheme::kColorId_DialogBackground);
 
   if (bg_color_override_) {
     bg_color = *bg_color_override_;
   } else if (is_prominent_) {
     bg_color = theme->GetSystemColor(
         ui::NativeTheme::kColorId_ProminentButtonColor);
@@ skipping 24 matching lines @@
   }
 
   DCHECK_EQ(SK_AlphaOPAQUE, static_cast<int>(SkColorGetA(bg_color)));
   SetBackground(
       CreateBackgroundFromPainter(Painter::CreateRoundRectWith1PxBorderPainter(
           bg_color, stroke_color, kInkDropSmallCornerRadius)));
   SchedulePaint();
 }
 
 }  // namespace views