Remove webrtc::ProtoString.

Bug: None
Change-Id: If99a977532eda41eada25f57ff0ff6fe17085986
Reviewed-on: https://webrtc-review.googlesource.com/c/122581
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Minyue Li <minyue@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26726}
diff --git a/modules/audio_coding/audio_network_adaptor/controller_manager.cc b/modules/audio_coding/audio_network_adaptor/controller_manager.cc
index 91c359d..4c0e61c 100644
--- a/modules/audio_coding/audio_network_adaptor/controller_manager.cc
+++ b/modules/audio_coding/audio_network_adaptor/controller_manager.cc
@@ -11,6 +11,7 @@
 #include "modules/audio_coding/audio_network_adaptor/controller_manager.h"
 
 #include <cmath>
+#include <string>
 #include <utility>
 
 #include "modules/audio_coding/audio_network_adaptor/bitrate_controller.h"
@@ -213,7 +214,7 @@
 ControllerManagerImpl::Config::~Config() = default;
 
 std::unique_ptr<ControllerManager> ControllerManagerImpl::Create(
-    const ProtoString& config_string,
+    const std::string& config_string,
     size_t num_encoder_channels,
     rtc::ArrayView<const int> encoder_frame_lengths_ms,
     int min_encoder_bitrate_bps,
@@ -229,7 +230,7 @@
 }
 
 std::unique_ptr<ControllerManager> ControllerManagerImpl::Create(
-    const ProtoString& config_string,
+    const std::string& config_string,
     size_t num_encoder_channels,
     rtc::ArrayView<const int> encoder_frame_lengths_ms,
     int min_encoder_bitrate_bps,