message: Use StrContains instead of find.
diff: #include <string>
  #include "absl/memory/memory.h"
  +#include "absl/strings/match.h"
  #include "tink/input_stream.h"
  #include "tink/subtle/subtle_util.h"
  #include "tink/util/status.h"
  @@ -34,7 +35,7 @@ namespace {
  bool is_eof(const util::Status& status) {
  return status.error_code() == util::error::UNKNOWN &&
  - status.error_message().find("EOFError") != std::string::npos;
  + absl::StrContains(status.error_message(), "EOFError");
  }
  } // namespace
  