First stab at MD text buttons

chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc

Index: chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc
diff --git a/chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc b/chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc
index 5cf2fa75993bbc18748e2921981b020623e7e462..371e13dd271ee0adf8075c54a0d265eb9965ac5f 100644
--- a/chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc
+++ b/chrome/browser/ui/libgtk2ui/native_theme_gtk2.cc
@@ -12,6 +12,7 @@
 #include "chrome/browser/ui/libgtk2ui/gtk2_util.h"
 #include "chrome/browser/ui/libgtk2ui/skia_utils_gtk2.h"
 #include "third_party/skia/include/core/SkColor.h"
+#include "ui/gfx/color_palette.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/size.h"
@@ -319,6 +320,10 @@ SkColor NativeThemeGtk2::GetSystemColor(ColorId color_id) const {
       // return GetTextColor(GetButton(), NORMAL);
     case kColorId_CallToActionColor:
       return GetSystemColor(kColorId_LinkEnabled);
+    // TODO(estade): set proper values for these.
+    case kColorId_MdTextButtonEnabledColor:
+    case kColorId_MdTextButtonDisabledColor:
+      return gfx::kPlaceholderColor;
 
     // Textfield
     case kColorId_TextfieldDefaultColor: