Convert ReplaceStringPlaceholders(std::string...) to take a

chrome/browser/dom_ui/dom_ui_theme_source.cc

Index: chrome/browser/dom_ui/dom_ui_theme_source.cc
diff --git a/chrome/browser/dom_ui/dom_ui_theme_source.cc b/chrome/browser/dom_ui/dom_ui_theme_source.cc
index f81193de4a037914c4193d6dc71282994e24a63f..49e227f2b6b8f7f3b595c05232affbe1c662ffad 100644
--- a/chrome/browser/dom_ui/dom_ui_theme_source.cc
+++ b/chrome/browser/dom_ui/dom_ui_theme_source.cc
@@ -193,9 +193,8 @@ void DOMUIThemeSource::InitNewTabCSS() {
       IDR_NEW_TAB_THEME_CSS));
 
   // Create the string from our template and the replacements.
-  std::string format_string = new_tab_theme_css.as_string();
   const std::string css_string = ReplaceStringPlaceholders(
-      format_string, subst, NULL);
+      new_tab_theme_css, subst, NULL);
   new_tab_css_ = ReplaceStringPlaceholders(
       css_string, subst2, NULL);
 }
@@ -227,9 +226,8 @@ void DOMUIThemeSource::InitNewIncognitoTabCSS() {
       IDR_NEW_INCOGNITO_TAB_THEME_CSS));
 
   // Create the string from our template and the replacements.
-  std::string format_string = new_tab_theme_css.as_string();
   new_incognito_tab_css_ = ReplaceStringPlaceholders(
-      format_string, subst, NULL);
+      new_tab_theme_css, subst, NULL);
 }
 
 void DOMUIThemeSource::SendNewTabCSS(int request_id,