Make it possible to build without enable_supervised_users.

chrome/browser/themes/theme_service.cc

Index: chrome/browser/themes/theme_service.cc
diff --git a/chrome/browser/themes/theme_service.cc b/chrome/browser/themes/theme_service.cc
index 0b7525c2f0d2db3a9d9d5f21a40412aa23ab0470..a29ca2151f8c2f95f469ac167c8ca7a693846da8 100644
--- a/chrome/browser/themes/theme_service.cc
+++ b/chrome/browser/themes/theme_service.cc
@@ -419,8 +419,6 @@ SkColor ThemeService::GetDefaultColor(int id, bool incognito) const {
   // For backward compat with older themes, some newer colors are generated from
   // older ones if they are missing.
   const int kNtpText = ThemeProperties::COLOR_NTP_TEXT;
-  const int kLabelBackground =
-      ThemeProperties::COLOR_SUPERVISED_USER_LABEL_BACKGROUND;
   switch (id) {
     case ThemeProperties::COLOR_TOOLBAR_BUTTON_ICON:
       return color_utils::HSLShift(
@@ -495,9 +493,12 @@ SkColor ThemeService::GetDefaultColor(int id, bool incognito) const {
       return color_utils::HSLShift(base_color, hsl);
     }
 #if BUILDFLAG(ENABLE_SUPERVISED_USERS)
-    case ThemeProperties::COLOR_SUPERVISED_USER_LABEL:
+    case ThemeProperties::COLOR_SUPERVISED_USER_LABEL: {
+      constexpr int kLabelBackground =
+          ThemeProperties::COLOR_SUPERVISED_USER_LABEL_BACKGROUND;
       return color_utils::GetReadableColor(
           SK_ColorWHITE, GetColor(kLabelBackground, incognito));
+    }
     case ThemeProperties::COLOR_SUPERVISED_USER_LABEL_BACKGROUND:
       return color_utils::BlendTowardOppositeLuma(
           GetColor(ThemeProperties::COLOR_FRAME, incognito), 0x80);