Restrict cross-thread access to gfx::Image and gfx::Font in ResourceBundle

ui/base/resource/resource_bundle.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 UI_BASE_RESOURCE_RESOURCE_BUNDLE_H_
 #define UI_BASE_RESOURCE_RESOURCE_BUNDLE_H_
 
 #include <stddef.h>
 
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/containers/hash_tables.h"
 #include "base/files/file_path.h"
 #include "base/files/memory_mapped_file.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/sequence_checker.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_piece.h"
 #include "build/build_config.h"
 #include "ui/base/layout.h"
 #include "ui/base/ui_base_export.h"
 #include "ui/gfx/font_list.h"
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/native_widget_types.h"
 
 class SkBitmap;
@@ skipping 356 matching lines @@
   // Returns an empty image for when a resource cannot be loaded. This is a
   // bright red bitmap.
   gfx::Image& GetEmptyImage();
 
   const base::FilePath& GetOverriddenPakPath();
 
   // This pointer is guaranteed to outlive the ResourceBundle instance and may
   // be NULL.
   Delegate* delegate_;
 
-  // Protects |images_| and font-related members.
-  std::unique_ptr<base::Lock> images_and_fonts_lock_;
-
   // Protects |locale_resources_data_|.
   std::unique_ptr<base::Lock> locale_resources_data_lock_;
 
   // Handles for data sources.
   std::unique_ptr<ResourceHandle> locale_resources_data_;
   std::vector<std::unique_ptr<ResourceHandle>> data_packs_;
 
   // The maximum scale factor currently loaded.
   ScaleFactor max_scale_factor_;
 
   // Cached images. The ResourceBundle caches all retrieved images and keeps
   // ownership of the pointers.
   typedef std::map<int, gfx::Image> ImageMap;
   ImageMap images_;
 
   gfx::Image empty_image_;
 
   // The various font lists used, as a map from a signed size delta from the
   // platform base font size, plus style, to the FontList. Cached to avoid
   // repeated GDI creation/destruction and font derivation.
-  // Must be accessed only while holding |images_and_fonts_lock_|.
+  // Must be accessed only from UI thread.
   std::map<FontKey, gfx::FontList> font_cache_;
 
   base::FilePath overridden_pak_path_;
 
   IdToStringMap overridden_locale_strings_;
 
   bool is_test_resources_ = false;
 
+  base::SequenceChecker sequence_checker_;
+
   DISALLOW_COPY_AND_ASSIGN(ResourceBundle);
 };
 
 }  // namespace ui
 
 // TODO(beng): Someday, maybe, get rid of this.
 using ui::ResourceBundle;
 
 #endif  // UI_BASE_RESOURCE_RESOURCE_BUNDLE_H_