message: Use opportunity to make extracted_facts_num const.
  Also, rename to previously_extracted_facts_num, to make
  the `return` line read like a sentence.
diff: @@ -367,7 +367,7 @@ void KytheFactsExtractor::ExtractFile(const IndexingFactNode& root) {
  bool KytheFactsExtractor::IndexingFactNodeTagResolver(
  const IndexingFactNode& node) {
  - size_t extracted_facts_num = seen_kythe_hashes_.size();
  + const size_t previously_extracted_facts_num = seen_kythe_hashes_.size();
  const auto tag = node.Value().GetIndexingFactType();
  // Dispatch a node handler based on the node's tag.
  @@ -487,7 +487,7 @@ bool KytheFactsExtractor::IndexingFactNodeTagResolver(
  CreateChildOfEdge(tag, vname);
  VisitAutoConstructScope(node, vname);
  - return seen_kythe_hashes_.size() > extracted_facts_num;
  + return seen_kythe_hashes_.size() > previously_extracted_facts_num;
  }
  void KytheFactsExtractor::AddDefinitionToCurrentScope(IndexingFactType tag,
  