Update package names to work with the proto3 compiler

Bug: b/28974522
Change-Id: I5f3adf4946ee4ba1e09e4f40afe83c151405972a
diff --git a/tools/aapt2/compile/Png.h b/tools/aapt2/compile/Png.h
index 01c9adb..aff1da3 100644
--- a/tools/aapt2/compile/Png.h
+++ b/tools/aapt2/compile/Png.h
@@ -62,8 +62,8 @@
   void BackUp(int count) override;
   bool Skip(int count) override;
 
-  int64_t ByteCount() const override {
-    return static_cast<int64_t>(window_start_);
+  google::protobuf::int64 ByteCount() const override {
+    return static_cast<google::protobuf::int64>(window_start_);
   }
 
   bool HadError() const override { return error_; }