Add support for auto-generated characteristics RRO

Setting use_rro_for_product will automatically generate an RRO package
which contains resources with 'product="{PRODUCT_CHARACTERISTICS}"'. The
RRO package will be installed to /product partition. The app will be
compiled with '--product default', making the app identical to all
targets.

Motivation for this change is to minimize divergence of system.img.

Bug: 294799593
Test: boot and idmap2 dump
Change-Id: I549c2589c69eab7a1568510a7d1ff0c8a003f7ea

core/artifact_path_requirements.mk

@@ -4,6 +4,7 @@
 # Fakes don't get installed, and NDK stubs aren't installed to device.
 static_allowed_patterns := $(TARGET_OUT_FAKE)/% $(SOONG_OUT_DIR)/ndk/%
 # RROs become REQUIRED by the source module, but are always placed on the vendor partition.
+static_allowed_patterns += %__auto_generated_characteristics_rro.apk
 static_allowed_patterns += %__auto_generated_rro_product.apk
 static_allowed_patterns += %__auto_generated_rro_vendor.apk
 # Auto-included targets are not considered

tools/Android.bp

@@ -96,3 +96,13 @@ python_test_host {
         unit_test: true,
     },
 }
+
+python_binary_host {
+  name: "characteristics_rro_generator",
+  srcs: ["characteristics_rro_generator.py"],
+  version: {
+    py3: {
+      embedded_launcher: true,
+    },
+  },
+}

tools/characteristics_rro_generator.py

@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+import sys
+from xml.dom.minidom import parseString
+
+def parse_package(manifest):
+    with open(manifest, 'r') as f:
+        data = f.read()
+    dom = parseString(data)
+    return dom.documentElement.getAttribute('package')
+
+if __name__ == '__main__':
+    if len(sys.argv) != 3:
+        sys.exit(f"usage: {sys_argv[0]} target_package_manifest output\n")
+    package_name = parse_package(sys.argv[1])
+    with open(sys.argv[2], "w") as f:
+        f.write(f'''<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="{package_name}.auto_generated_characteristics_rro">
+    <application android:hasCode="false" />
+    <overlay android:targetPackage="{package_name}"
+             android:isStatic="true"
+             android:priority="0" />
+</manifest>
+''')