Make sure Proguard keeps zygote preload class.

Bug: 127262679
Test: atest ProguardRulesTest
Change-Id: Ib082404e08d98b25fcecbf680afb4af37fe2786b
diff --git a/tools/aapt2/java/ProguardRules.cpp b/tools/aapt2/java/ProguardRules.cpp
index 52e168e..05ba8f0 100644
--- a/tools/aapt2/java/ProguardRules.cpp
+++ b/tools/aapt2/java/ProguardRules.cpp
@@ -281,6 +281,15 @@
             AddClass(node->line_number, result.value(), "");
           }
         }
+
+        attr = node->FindAttribute(xml::kSchemaAndroid, "zygotePreloadName");
+        if (attr) {
+          Maybe<std::string> result = util::GetFullyQualifiedClassName(package_, attr->value);
+          if (result) {
+            AddClass(node->line_number, result.value(), "");
+          }
+        }
+
         if (main_dex_only_) {
           xml::Attribute* default_process = node->FindAttribute(xml::kSchemaAndroid, "process");
           if (default_process) {