AAPT2: Fix escaping sequence processing in XML parsing

Bug: 35483813
Test: make aapt2_tests
Change-Id: I68baba17ab3639c220b734a2a68d86aad0dedf8c
diff --git a/tools/aapt2/util/Util.h b/tools/aapt2/util/Util.h
index f8fa80e..7210d21 100644
--- a/tools/aapt2/util/Util.h
+++ b/tools/aapt2/util/Util.h
@@ -164,6 +164,7 @@
   StringBuilder& Append(const android::StringPiece& str);
   const std::string& ToString() const;
   const std::string& Error() const;
+  bool IsEmpty() const;
 
   // When building StyledStrings, we need UTF-16 indices into the string,
   // which is what the Java layer expects when dealing with java
@@ -185,6 +186,8 @@
 
 inline const std::string& StringBuilder::Error() const { return error_; }
 
+inline bool StringBuilder::IsEmpty() const { return str_.empty(); }
+
 inline size_t StringBuilder::Utf16Len() const { return utf16_len_; }
 
 inline StringBuilder::operator bool() const { return error_.empty(); }