Fix Chromium clang plugin warnings

webrtc/modules/audio_processing/agc/agc.cc

Index: webrtc/modules/audio_processing/agc/agc.cc
diff --git a/webrtc/modules/audio_processing/agc/agc.cc b/webrtc/modules/audio_processing/agc/agc.cc
index 9de17059625767b768f201fb44fe4a4ae46641a9..2bff7359f814070900ea260b1cada5e99712fa90 100644
--- a/webrtc/modules/audio_processing/agc/agc.cc
+++ b/webrtc/modules/audio_processing/agc/agc.cc
@@ -97,4 +97,12 @@ int Agc::set_target_level_dbfs(int level) {
   return 0;
 }
 
+int Agc::target_level_dbfs() const {
+  return target_level_dbfs_;
+}
+
+float Agc::voice_probability() const {
+  return vad_.last_voice_probability();
+}
+
 }  // namespace webrtc