Creating controller manager from config string in audio network adaptor.

webrtc/modules/audio_coding/audio_network_adaptor/fec_controller.h

Index: webrtc/modules/audio_coding/audio_network_adaptor/fec_controller.h
diff --git a/webrtc/modules/audio_coding/audio_network_adaptor/fec_controller.h b/webrtc/modules/audio_coding/audio_network_adaptor/fec_controller.h
index 17aa65f1e68f2ffd1aa1d75ddae90f40933dcf35..0c2388b2c6ce41e04bbce1d7aff920a2a80929fb 100644
--- a/webrtc/modules/audio_coding/audio_network_adaptor/fec_controller.h
+++ b/webrtc/modules/audio_coding/audio_network_adaptor/fec_controller.h
@@ -56,12 +56,12 @@ class FecController final : public Controller {
            const Threshold& fec_enabling_threshold,
            const Threshold& fec_disabling_threshold,
            int time_constant_ms,
-           Clock* clock);
+           const Clock* clock);
     bool initial_fec_enabled;
     Threshold fec_enabling_threshold;
     Threshold fec_disabling_threshold;
     int time_constant_ms;
-    Clock* clock;
+    const Clock* clock;
   };
 
   explicit FecController(const Config& config);