Try 2: Completely redo how themes are stored on disk and processed at install time.

base/data_pack.h

Index: base/data_pack.h
diff --git a/base/data_pack.h b/base/data_pack.h
index 7c9abde941e25ace46890b14da027e0d072fc55c..893849141003536fc1cfd905d5419bf9c9d9bed5 100644
--- a/base/data_pack.h
+++ b/base/data_pack.h
@@ -9,6 +9,8 @@
 #ifndef BASE_DATA_PACK_H_
 #define BASE_DATA_PACK_H_
 
+#include <map>
+
 #include "base/basictypes.h"
 #include "base/ref_counted_memory.h"
 #include "base/scoped_ptr.h"
@@ -33,12 +35,16 @@ class DataPack {
   // 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_t resource_id, StringPiece* data);
+  bool GetStringPiece(uint32 resource_id, StringPiece* data);
 
   // 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_t resource_id);
+  RefCountedStaticMemory* GetStaticMemory(uint32 resource_id);
+
+  // Writes a pack file containing |resources| to |path|.
+  static bool WritePack(const FilePath& path,
+                        const std::map<uint32, StringPiece>& resources);
 
  private:
   // The memory-mapped data.