Remove the enable_themes build flag and define.

chrome/browser/ui/webui/signin/md_user_manager_ui.cc

Index: chrome/browser/ui/webui/signin/md_user_manager_ui.cc
diff --git a/chrome/browser/ui/webui/signin/md_user_manager_ui.cc b/chrome/browser/ui/webui/signin/md_user_manager_ui.cc
index db5c76e7655a1042d4d128022447c3c7a7c2cc97..51bb97e165c054000fea0b665f2d82aecd17a631 100644
--- a/chrome/browser/ui/webui/signin/md_user_manager_ui.cc
+++ b/chrome/browser/ui/webui/signin/md_user_manager_ui.cc
@@ -48,11 +48,9 @@ MDUserManagerUI::MDUserManagerUI(content::WebUI* web_ui)
   // Set up the chrome://md-user-manager/ source.
   content::WebUIDataSource::Add(profile, CreateUIDataSource(localized_strings));
 
-#if defined(ENABLE_THEMES)
   // Set up the chrome://theme/ source
   ThemeSource* theme = new ThemeSource(profile);
   content::URLDataSource::Add(profile, theme);
-#endif
 }
 
 MDUserManagerUI::~MDUserManagerUI() {}