message: [TF:XLA] virtualize some methods in copy insertion
diff: @@ -94,10 +94,12 @@ class CopyInsertion : public HloModulePass {
  Status VerifyNoLiveRangeInterference(const HloOrdering& ordering,
  HloModule* module);
  - private:
  + protected:
  // Override which requires the caller to pass in a call graph.
  - Status AddSpecialCaseCopies(const CallGraph& call_graph, HloModule* module);
  + virtual Status AddSpecialCaseCopies(const CallGraph& call_graph,
  + HloModule* module);
  + private:
  Status AddCopiesToResolveInterference(HloModule* module);
  // Backend specific function that decides whether a fusion can share buffer
  