Add methods to add DataPack from open files

ui/base/resource/data_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.
 
 // DataPack represents a read-only view onto an on-disk file that contains
 // (key, value) pairs of data.  It's used to store static resources like
 // translation strings and images.
 
 #ifndef UI_BASE_RESOURCE_DATA_PACK_H_
 #define UI_BASE_RESOURCE_DATA_PACK_H_
 #pragma once
 
 #include <map>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/platform_file.h"
 #include "base/string_piece.h"
 #include "ui/base/layout.h"
 #include "ui/base/resource/resource_handle.h"
 #include "ui/base/ui_export.h"
 
 class FilePath;
 
 namespace base {
 class RefCountedStaticMemory;
 }
 
 namespace file_util {
 class MemoryMappedFile;
 }
 
 namespace ui {
 
 class UI_EXPORT DataPack : public ResourceHandle {
  public:
   DataPack(ui::ScaleFactor scale_factor);
   virtual ~DataPack();
 
   // Load a pack file from |path|, returning false on error.
-  bool Load(const FilePath& path);
+  bool LoadFromPath(const FilePath& path);
+
+  // Loads a pack file from |file|, returning false on error.
+  bool LoadFromFile(base::PlatformFile file);
 
   // Writes a pack file containing |resources| to |path|. If there are any
   // text resources to be written, their encoding must already agree to the
   // |textEncodingType| specified. If no text resources are present, please
   // indicate BINARY.
   static bool WritePack(const FilePath& path,
                         const std::map<uint16, base::StringPiece>& resources,
                         TextEncodingType textEncodingType);
 
   // ResourceHandle implementation:
   virtual bool HasResource(uint16 resource_id) const OVERRIDE;
   virtual bool GetStringPiece(uint16 resource_id,
                               base::StringPiece* data) const OVERRIDE;
   virtual base::RefCountedStaticMemory* GetStaticMemory(
       uint16 resource_id) const OVERRIDE;
   virtual TextEncodingType GetTextEncodingType() const OVERRIDE;
   virtual ui::ScaleFactor GetScaleFactor() const OVERRIDE;
 
  private:
+  // Does the actual loading of a pack file. Called by Load and LoadFromFile.
+  bool LoadImpl();
+
   // The memory-mapped data.
   scoped_ptr<file_util::MemoryMappedFile> mmap_;
 
   // Number of resources in the data.
   size_t resource_count_;
 
   // Type of encoding for text resources.
   TextEncodingType text_encoding_type_;
 
   // The scale of the image in this resource pack relative to images in the 1x
   // resource pak.
   ui::ScaleFactor scale_factor_;
 
   DISALLOW_COPY_AND_ASSIGN(DataPack);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_RESOURCE_DATA_PACK_H_