Various optimizations to reduce the number of temporary allocations.

chrome/browser/themes/browser_theme_pack.h

Index: chrome/browser/themes/browser_theme_pack.h
diff --git a/chrome/browser/themes/browser_theme_pack.h b/chrome/browser/themes/browser_theme_pack.h
index effba56c166599aab5ef5163127d2d172eaf5c25..8d5bdaa823f96db55f48213d158bc6e23c8ef88a 100644
--- a/chrome/browser/themes/browser_theme_pack.h
+++ b/chrome/browser/themes/browser_theme_pack.h
@@ -67,9 +67,8 @@ class BrowserThemePack : public CustomThemeSupplier {
   static scoped_refptr<BrowserThemePack> BuildFromDataPack(
       const base::FilePath& path, const std::string& expected_id);
 
-  // Returns the set of image IDRs which can be overwritten by a user provided
-  // theme.
-  static void GetThemeableImageIDRs(std::set<int>* result);
+  // Returns true if an IDR exists.
+  static bool IsThemeableImageIDRs(int id);
 
   // Builds a data pack on disk at |path| for future quick loading by
   // BuildFromDataPack(). Often (but not always) called from the file thread;