Various optimizations to reduce the number of temporary allocations.

chrome/browser/themes/browser_theme_pack.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_THEMES_BROWSER_THEME_PACK_H_
 #define CHROME_BROWSER_THEMES_BROWSER_THEME_PACK_H_
 
 #include <map>
 #include <string>
 #include <vector>
@@ skipping 49 matching lines @@
   // the case where the theme has invalid data.
   static scoped_refptr<BrowserThemePack> BuildFromExtension(
       const extensions::Extension* extension);
 
   // Builds the theme pack from a previously performed WriteToDisk(). This
   // operation should be relatively fast, as it should be an mmap() and some
   // pointer swizzling. Returns NULL on any error attempting to read |path|.
   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 whether the specified identifier is one of the images we persist
+  // in the data pack.
+  static bool IsPersistentImageID(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;
   // implementation should be threadsafe because neither thread will write to
   // |image_memory_| and the worker thread will keep a reference to prevent
   // destruction.
   bool WriteToDisk(const base::FilePath& path) const;
 
   // Overridden from CustomThemeSupplier:
   bool GetTint(int id, color_utils::HSL* hsl) const override;
@@ skipping 185 matching lines @@
   // Cache of images created in BuildFromExtension(). Once the theme pack is
   // created, this cache should only be accessed on the file thread. There
   // should be no IDs in |image_memory_| that are in |images_on_file_thread_|
   // or vice versa.
   ImageCache images_on_file_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserThemePack);
 };
 
 #endif  // CHROME_BROWSER_THEMES_BROWSER_THEME_PACK_H_