AAPT2: Convert binary ResTable_config to proto

Test: make aapt2_tests
Change-Id: I8641f13ce41cd58ac8bc3da31c4e15a7b3f06092
diff --git a/tools/aapt2/ConfigDescription.h b/tools/aapt2/ConfigDescription.h
index 65c9617..c1d0e10 100644
--- a/tools/aapt2/ConfigDescription.h
+++ b/tools/aapt2/ConfigDescription.h
@@ -61,6 +61,9 @@
 
   ConfigDescription CopyWithoutSdkVersion() const;
 
+  // Returns the BCP-47 language tag of this configuration's locale.
+  std::string GetBcp47LanguageTag(bool canonicalize = false) const;
+
   /**
    * A configuration X dominates another configuration Y, if X has at least the
    * precedence of Y and X is strictly more general than Y: for any type defined