AAPT2: Switch to protobuf for intermediate format

Without needing to conform to the runtime data format,
it is much easier to add new features such as debugging symbols
and carrying over product data to link time.

This also simplifies the runtime format parser and serializer,
which will change much less frequently than the protobuf intermediate
format.

Change-Id: I209787bbf087db0a58a534cb8511c51d21133e00
diff --git a/tools/aapt2/ResourceUtils.h b/tools/aapt2/ResourceUtils.h
index 64ca971..a0fbcc6 100644
--- a/tools/aapt2/ResourceUtils.h
+++ b/tools/aapt2/ResourceUtils.h
@@ -45,7 +45,8 @@
  * `outResource` set to the parsed resource name and `outPrivate` set to true if a '*' prefix
  * was present.
  */
-bool parseResourceName(const StringPiece16& str, ResourceNameRef* outResource, bool* outPrivate);
+bool parseResourceName(const StringPiece16& str, ResourceNameRef* outResource,
+                       bool* outPrivate = nullptr);
 
 /*
  * Returns true if the string was parsed as a reference (@[+][package:]type/name), with