Update the .pak file format to version 2: Make resource ids 16bit

ui/base/resource/data_pack.h

 // Copyright (c) 2011 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_
@@ skipping 22 matching lines @@
  public:
   DataPack();
   ~DataPack();
 
   // Load a pack file from |path|, returning false on error.
   bool Load(const FilePath& path);
 
   // Get resource by id |resource_id|, filling in |data|.
   // The data is owned by the DataPack object and should not be modified.
   // Returns false if the resource id isn't found.
-  bool GetStringPiece(uint32 resource_id, base::StringPiece* data) const;
+  bool GetStringPiece(uint16 resource_id, base::StringPiece* data) const;
 
   // Like GetStringPiece(), but returns a reference to memory. This interface
   // is used for image data, while the StringPiece interface is usually used
   // for localization strings.
-  RefCountedStaticMemory* GetStaticMemory(uint32 resource_id) const;
+  RefCountedStaticMemory* GetStaticMemory(uint16 resource_id) const;
 
   // Writes a pack file containing |resources| to |path|.
   static bool WritePack(const FilePath& path,
-                        const std::map<uint32, base::StringPiece>& resources);
+                        const std::map<uint16, base::StringPiece>& resources);
 
  private:
   // The memory-mapped data.
   scoped_ptr<file_util::MemoryMappedFile> mmap_;
 
   // Number of resources in the data.
   size_t resource_count_;
 
   DISALLOW_COPY_AND_ASSIGN(DataPack);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_RESOURCE_DATA_PACK_H_