Revert "Use reference counted pointers for ApkAssets"

This reverts commit c357f719ed3734aee05418808699a48dd150a1a5.

Reason for revert: b/279154343 - performance regression

Change-Id: If2e212d8fc5b9ed8638032a33f450440cbaeceb0
diff --git a/cmds/idmap2/libidmap2/ResourceContainer.cpp b/cmds/idmap2/libidmap2/ResourceContainer.cpp
index 7869fbd..0e35904 100644
--- a/cmds/idmap2/libidmap2/ResourceContainer.cpp
+++ b/cmds/idmap2/libidmap2/ResourceContainer.cpp
@@ -262,7 +262,7 @@
 }
 
 struct ResState {
-  AssetManager2::ApkAssetsPtr apk_assets;
+  std::unique_ptr<ApkAssets> apk_assets;
   const LoadedArsc* arsc;
   const LoadedPackage* package;
   std::unique_ptr<AssetManager2> am;
@@ -284,7 +284,7 @@
     }
 
     state.am = std::make_unique<AssetManager2>();
-    if (!state.am->SetApkAssets({state.apk_assets})) {
+    if (!state.am->SetApkAssets({state.apk_assets.get()})) {
       return Error("failed to create asset manager");
     }