Switch the Clang plugin to use RecursiveASTVisitor.

tools/clang/plugins/ChromeClassTester.h

Index: tools/clang/plugins/ChromeClassTester.h
diff --git a/tools/clang/plugins/ChromeClassTester.h b/tools/clang/plugins/ChromeClassTester.h
index 6bd19a629a8248d9539286653e74e33e393ff7b8..963b90fac2e4ee81199a763014ac04840fdb63d2 100644
--- a/tools/clang/plugins/ChromeClassTester.h
+++ b/tools/clang/plugins/ChromeClassTester.h
@@ -23,6 +23,8 @@ class ChromeClassTester : public clang::ASTConsumer {
   virtual void HandleTagDeclDefinition(clang::TagDecl* tag);
   virtual bool HandleTopLevelDecl(clang::DeclGroupRef group_ref);
 
+  void CheckTag(clang::TagDecl*);
+
  protected:
   clang::CompilerInstance& instance() { return instance_; }
   clang::DiagnosticsEngine& diagnostic() { return diagnostic_; }
@@ -47,8 +49,6 @@ class ChromeClassTester : public clang::ASTConsumer {
  private:
   void BuildBannedLists();
 
-  void CheckTag(clang::TagDecl*);
-
   // Filtered versions of tags that are only called with things defined in
   // chrome header files.
   virtual void CheckChromeClass(clang::SourceLocation record_location,