GetSupportedAnnotations protected

String values of annotations are only visible within aidl_language.cpp.

Bug: N/A
Test: compile
Change-Id: I2ae5ac8948d3970aa460cafc19d9872ae0e2d58e
diff --git a/aidl_language.h b/aidl_language.h
index 16822b0..3780e4a 100644
--- a/aidl_language.h
+++ b/aidl_language.h
@@ -271,9 +271,11 @@
   std::string ToString() const;
 
   const vector<AidlAnnotation>& GetAnnotations() const { return annotations_; }
-  virtual std::set<string> GetSupportedAnnotations() const = 0;
   virtual bool CheckValid(const AidlTypenames&) const;
 
+ protected:
+  virtual std::set<string> GetSupportedAnnotations() const = 0;
+
  private:
   vector<AidlAnnotation> annotations_;
 };