Surface <overlayable> info in Java AssetManager

Add a new, hidden method to AssetManager to extract a mapping
overlayable name -> overlayable actor for all <overlayable> blocks in a
package. [This will eventually be used to check if the caller of the OMS
AIDL API is the registered actor for a given overlay.]

Also, teach AssetManager2 to not accept packages that re-use the same
overlayable name. [Such packages have always been ill-formed.]

Bug: 123894537
Test: make libandroidfw_tests
Change-Id: I1117fd3503f04fe4c73eb7114901e022508f4d9e
diff --git a/libs/androidfw/tests/LoadedArsc_test.cpp b/libs/androidfw/tests/LoadedArsc_test.cpp
index b8d3c6b..d58e8d2 100644
--- a/libs/androidfw/tests/LoadedArsc_test.cpp
+++ b/libs/androidfw/tests/LoadedArsc_test.cpp
@@ -331,7 +331,7 @@
 
   const std::vector<std::unique_ptr<const LoadedPackage>>& packages = loaded_arsc->GetPackages();
   ASSERT_EQ(1u, packages.size());
-  EXPECT_EQ(std::string("com.android.basic"), packages[0]->GetPackageName());
+  ASSERT_EQ(std::string("com.android.basic"), packages[0]->GetPackageName());
 
   const auto& loaded_package = packages[0];
   auto iter = loaded_package->begin();
@@ -369,6 +369,24 @@
   ASSERT_EQ(end, iter);
 }
 
+TEST(LoadedArscTest, GetOverlayableMap) {
+  std::string contents;
+  ASSERT_TRUE(ReadFileFromZipToString(GetTestDataPath() + "/overlayable/overlayable.apk",
+                                      "resources.arsc", &contents));
+
+  std::unique_ptr<const LoadedArsc> loaded_arsc = LoadedArsc::Load(StringPiece(contents));
+  ASSERT_NE(nullptr, loaded_arsc);
+
+  const std::vector<std::unique_ptr<const LoadedPackage>>& packages = loaded_arsc->GetPackages();
+  ASSERT_EQ(1u, packages.size());
+  ASSERT_EQ(std::string("com.android.overlayable"), packages[0]->GetPackageName());
+
+  const auto map = packages[0]->GetOverlayableMap();
+  ASSERT_EQ(2, map.size());
+  ASSERT_EQ(map.at("OverlayableResources1"), "overlay://theme");
+  ASSERT_EQ(map.at("OverlayableResources2"), "overlay://com.android.overlayable");
+}
+
 // structs with size fields (like Res_value, ResTable_entry) should be
 // backwards and forwards compatible (aka checking the size field against
 // sizeof(Res_value) might not be backwards compatible.