[MD User Menu] Adjusted its background color

ui/native_theme/native_theme_win.cc

Index: ui/native_theme/native_theme_win.cc
diff --git a/ui/native_theme/native_theme_win.cc b/ui/native_theme/native_theme_win.cc
index ce865996b534254d4ea8f2ba9bf7631511f01b3c..043a3d47278a278e01d1c455157a9ae06ceec4b9 100644
--- a/ui/native_theme/native_theme_win.cc
+++ b/ui/native_theme/native_theme_win.cc
@@ -493,6 +493,8 @@ SkColor NativeThemeWin::GetSystemColor(ColorId color_id) const {
     // Dialogs
     case kColorId_DialogBackground:
     case kColorId_BubbleBackground:
+      if (ui::MaterialDesignController::IsSecondaryUiMaterial())
+        break;
       return color_utils::IsInvertedColorScheme() ?
           color_utils::InvertColor(kDialogBackgroundColor) :
           kDialogBackgroundColor;