Revert "Enforce a default policy on packages without <overlayable>"

This reverts commit 48945224bdc298630c76befdb50a31838bdafd8e.

Reason for revert: <b/127835630>

Change-Id: I0bc90c26e5b7d6b4d94704a2a1f92bbc889c025c
diff --git a/cmds/idmap2/libidmap2/Idmap.cpp b/cmds/idmap2/libidmap2/Idmap.cpp
index f4c3e9c..a1341fb 100644
--- a/cmds/idmap2/libidmap2/Idmap.cpp
+++ b/cmds/idmap2/libidmap2/Idmap.cpp
@@ -287,20 +287,11 @@
 bool CheckOverlayable(const LoadedPackage& target_package,
                       const utils::OverlayManifestInfo& overlay_info,
                       const PolicyBitmask& fulfilled_policies, const ResourceId& resid) {
-  static constexpr const PolicyBitmask sDefaultPolicies =
-      PolicyFlags::POLICY_SYSTEM_PARTITION | PolicyFlags::POLICY_VENDOR_PARTITION |
-      PolicyFlags::POLICY_PRODUCT_PARTITION | PolicyFlags::POLICY_SIGNATURE;
-
-  // If the resource does not have an overlayable definition, allow the resource to be overlaid if
-  // the overlay is preinstalled or signed with the same signature as the target.
-  if (!target_package.DefinesOverlayable()) {
-    return (sDefaultPolicies & fulfilled_policies) != 0;
-  }
-
   const OverlayableInfo* overlayable_info = target_package.GetOverlayableInfo(resid);
   if (overlayable_info == nullptr) {
-    // Do not allow non-overlayable resources to be overlaid.
-    return false;
+    // If the resource does not have an overlayable definition, allow the resource to be overlaid.
+    // Once overlayable enforcement is turned on, this check will return false.
+    return !target_package.DefinesOverlayable();
   }
 
   if (overlay_info.target_name != overlayable_info->name) {
@@ -436,12 +427,6 @@
     matching_resources.Add(target_resid, overlay_resid);
   }
 
-  if (matching_resources.Map().empty()) {
-    out_error << "overlay \"" << overlay_apk_path << "\" does not successfully overlay any resource"
-              << std::endl;
-    return nullptr;
-  }
-
   // encode idmap data
   std::unique_ptr<IdmapData> data(new IdmapData());
   const auto types_end = matching_resources.Map().cend();