Revert of Loosening the coupling between WebRTC and //third_party/protobuf

webrtc/modules/audio_coding/audio_network_adaptor/controller_manager_unittest.cc

Index: webrtc/modules/audio_coding/audio_network_adaptor/controller_manager_unittest.cc
diff --git a/webrtc/modules/audio_coding/audio_network_adaptor/controller_manager_unittest.cc b/webrtc/modules/audio_coding/audio_network_adaptor/controller_manager_unittest.cc
index 292f17f1746862582a93a448dafa4ccb0c3cb72f..ed96e1b9c689ec37793d9306cfeccd544de2b399 100644
--- a/webrtc/modules/audio_coding/audio_network_adaptor/controller_manager_unittest.cc
+++ b/webrtc/modules/audio_coding/audio_network_adaptor/controller_manager_unittest.cc
@@ -11,7 +11,6 @@
 #include <utility>
 
 #include "webrtc/base/ignore_wundef.h"
-#include "webrtc/base/protobuf_utils.h"
 #include "webrtc/modules/audio_coding/audio_network_adaptor/controller_manager.h"
 #include "webrtc/modules/audio_coding/audio_network_adaptor/mock/mock_controller.h"
 #include "webrtc/system_wrappers/include/clock.h"
@@ -274,7 +273,7 @@
 constexpr int kMinBitrateBps = 6000;
 
 ControllerManagerStates CreateControllerManager(
-    const ProtoString& config_string) {
+    const std::string& config_string) {
   ControllerManagerStates states;
   states.simulated_clock.reset(new SimulatedClock(kClockInitialTime));
   constexpr size_t kNumEncoderChannels = 2;
@@ -346,7 +345,7 @@
   AddFrameLengthControllerConfig(&config);
   AddBitrateControllerConfig(&config);
 
-  ProtoString config_string;
+  std::string config_string;
   config.SerializeToString(&config_string);
 
   auto states = CreateControllerManager(config_string);
@@ -377,7 +376,7 @@
 
   AddBitrateControllerConfig(&config);
 
-  ProtoString config_string;
+  std::string config_string;
   config.SerializeToString(&config_string);
 
   auto states = CreateControllerManager(config_string);