Add support for loading pak files from arbitrary file regions.

ui/base/resource/resource_bundle.cc

 // 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.
 
 #include "ui/base/resource/resource_bundle.h"
 
 #include <limits>
 #include <vector>
 
 #include "base/big_endian.h"
@@ skipping 216 matching lines @@
   AddDataPackFromPathInternal(path, scale_factor, false);
 }
 
 void ResourceBundle::AddOptionalDataPackFromPath(const base::FilePath& path,
                                          ScaleFactor scale_factor) {
   AddDataPackFromPathInternal(path, scale_factor, true);
 }
 
 void ResourceBundle::AddDataPackFromFile(base::File file,
                                          ScaleFactor scale_factor) {
+  AddDataPackFromFileRegion(
+      file.Pass(), base::MemoryMappedFile::Region::kWholeFile, scale_factor);
+}
+
+void ResourceBundle::AddDataPackFromFileRegion(
+    base::File file,
+    const base::MemoryMappedFile::Region& region,
+    ScaleFactor scale_factor) {
   scoped_ptr<DataPack> data_pack(
       new DataPack(scale_factor));
-  if (data_pack->LoadFromFile(file.Pass())) {
+  if (data_pack->LoadFromFileRegion(file.Pass(), region)) {
     AddDataPack(data_pack.release());
   } else {
     LOG(ERROR) << "Failed to load data pack from file."
                << "\nSome features may not be available.";
   }
 }
 
 #if !defined(OS_MACOSX)
 base::FilePath ResourceBundle::GetLocaleFilePath(const std::string& app_locale,
                                                  bool test_file_exists) {
@@ skipping 583 matching lines @@
 // static
 bool ResourceBundle::DecodePNG(const unsigned char* buf,
                                size_t size,
                                SkBitmap* bitmap,
                                bool* fell_back_to_1x) {
   *fell_back_to_1x = PNGContainsFallbackMarker(buf, size);
   return gfx::PNGCodec::Decode(buf, size, bitmap);
 }
 
 }  // namespace ui