Remove USE_BASE_DATA_PACK from build_config.h since it's only

ui/base/resource/resource_bundle.h

Index: ui/base/resource/resource_bundle.h
diff --git a/ui/base/resource/resource_bundle.h b/ui/base/resource/resource_bundle.h
index 692a3aab934f44db7f2dde52c5783c2cb1a2dfbd..85aee337b5d29cc6d68c84913d9b8c51fa75630e 100644
--- a/ui/base/resource/resource_bundle.h
+++ b/ui/base/resource/resource_bundle.h
@@ -207,8 +207,8 @@ class UI_API ResourceBundle {
 #if defined(OS_WIN)
   // Windows stores resources in DLLs, which are managed by HINSTANCE.
   typedef HINSTANCE DataHandle;
-#elif defined(USE_BASE_DATA_PACK)
-  // Linux uses base::DataPack.
+#elif defined(OS_POSIX)
+  // Everyone else uses base::DataPack.
   typedef DataPack* DataHandle;
 #endif
 
@@ -236,7 +236,7 @@ class UI_API ResourceBundle {
   // Initialize all the gfx::Font members if they haven't yet been initialized.
   void LoadFontsIfNecessary();
 
-#if defined(USE_BASE_DATA_PACK)
+#if defined(OS_POSIX)
   // Returns the full pathname of the main resources file to load.  May return
   // an empty string if no main resources data files are found.
   static FilePath GetResourcesFilePath();