message: Add comment flagging people towards Env::LocalTempFilename instead of testing::TmpDir
diff: @@ -34,6 +34,8 @@ namespace tensorflow {
  namespace testing {
  // Return a temporary directory suitable for temporary testing files.
  +//
  +// Where possible, consider using Env::LocalTempFilename over this function.
  string TmpDir();
  // Returns the path to TensorFlow in the directory containing data
  