[clang-tidy] Apply performance-for-range-copy fixes.

This CL applies clang-tidy's performance-for-range-copy [1] on the
WebRTC codebase.

All changes in this CL are automatically generated by both clang-tidy
and 'git cl format'.

[1] - https://clang.llvm.org/extra/clang-tidy/checks/performance-for-range-copy.html

Bug: webrtc:10215
Change-Id: I7c83290b8866d76129bbec4e24e6701f5014102e
Reviewed-on: https://webrtc-review.googlesource.com/c/120043
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26420}
diff --git a/test/call_config_utils.cc b/test/call_config_utils.cc
index 671220b..af9ca11 100644
--- a/test/call_config_utils.cc
+++ b/test/call_config_utils.cc
@@ -22,7 +22,7 @@
     webrtc::Transport* transport,
     const Json::Value& json) {
   auto receive_config = VideoReceiveStream::Config(transport);
-  for (const auto decoder_json : json["decoders"]) {
+  for (const auto& decoder_json : json["decoders"]) {
     VideoReceiveStream::Decoder decoder;
     decoder.video_format =
         SdpVideoFormat(decoder_json["payload_name"].asString());