Add SetProminent() to MdTextButton to create blue buttons.

ui/native_theme/native_theme_dark_aura.cc

Index: ui/native_theme/native_theme_dark_aura.cc
diff --git a/ui/native_theme/native_theme_dark_aura.cc b/ui/native_theme/native_theme_dark_aura.cc
index 305388e0f72917c653ac8490644c13a88db9627b..4683a65be010eb8a37e15ca7b9dbbe451e2659c9 100644
--- a/ui/native_theme/native_theme_dark_aura.cc
+++ b/ui/native_theme/native_theme_dark_aura.cc
@@ -39,7 +39,7 @@ SkColor NativeThemeDarkAura::GetSystemColor(ColorId color_id) const {
     // Button
     case kColorId_ButtonEnabledColor:
       return kButtonEnabledColor;
-    case kColorId_CallToActionColor:
+    case kColorId_ProminentButtonColor:
       return gfx::kGoogleBlue300;
 
     // Label
@@ -88,7 +88,7 @@ SkColor NativeThemeDarkAura::GetSystemColor(ColorId color_id) const {
 
     // Intentional pass-throughs to NativeThemeAura.
     case kColorId_LabelDisabledColor:
-    case kColorId_TextOnCallToActionColor:
+    case kColorId_TextOnProminentButtonColor:
     case kColorId_ButtonPressedShade:
     case kColorId_ResultsTableHoveredBackground:
     case kColorId_ResultsTableSelectedBackground: