Change uses of base::JoinString to pass StringPieces where possible.

chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc

Index: chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc
diff --git a/chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc b/chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc
index 1fc8b48d1b7b69760934cc6b6fb9ab07df17f9fe..0af420416e6171dbc594f1467c1cec8a2991bfb0 100644
--- a/chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc
+++ b/chrome/browser/extensions/api/networking_private/crypto_verify_impl.cc
@@ -11,6 +11,7 @@
 #include "base/bind_helpers.h"
 #include "base/sequenced_task_runner.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/threading/sequenced_worker_pool.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ -166,13 +167,10 @@ CryptoVerifyImpl::Credentials::Credentials(
     intermediate_certificates = *properties.intermediate_certificates;
   signed_data = properties.signed_data;
 
-  std::vector<std::string> data_parts;
-  data_parts.push_back(properties.device_ssid);
-  data_parts.push_back(properties.device_serial);
-  data_parts.push_back(properties.device_bssid);
-  data_parts.push_back(properties.public_key);
-  data_parts.push_back(properties.nonce);
-  unsigned_data = base::JoinString(data_parts, ",");
+  unsigned_data = base::JoinString(
+      {properties.device_ssid, properties.device_serial,
+       properties.device_bssid, properties.public_key, properties.nonce},
+      ",");
 
   device_bssid = properties.device_bssid;
   public_key = properties.public_key;