AAPT2: Support generating Manifest.java

This includes comments from AndroidManifest.xml.

Change-Id: I412d9ecb12bad20a49a683d6b3bea4a0be1235ae
diff --git a/tools/aapt2/XmlDom.h b/tools/aapt2/XmlDom.h
index c095f08..b1987f1 100644
--- a/tools/aapt2/XmlDom.h
+++ b/tools/aapt2/XmlDom.h
@@ -132,6 +132,8 @@
 std::unique_ptr<XmlResource> inflate(const void* data, size_t dataLen, IDiagnostics* diag,
                                      const Source& source);
 
+Element* findRootElement(Node* node);
+
 /**
  * A visitor interface for the different XML Node subtypes. This will not traverse into
  * children. Use Visitor for that.