Fix Chromium clang plugin warnings

webrtc/modules/audio_processing/agc/agc.h

Index: webrtc/modules/audio_processing/agc/agc.h
diff --git a/webrtc/modules/audio_processing/agc/agc.h b/webrtc/modules/audio_processing/agc/agc.h
index 59faba6866ee3496c5fd3b57fbb0f548f1927ed6..e681e376de2435b0b14419e19a58237c8c9a3361 100644
--- a/webrtc/modules/audio_processing/agc/agc.h
+++ b/webrtc/modules/audio_processing/agc/agc.h
@@ -40,11 +40,8 @@ class Agc {
   virtual void Reset();
 
   virtual int set_target_level_dbfs(int level);
-  virtual int target_level_dbfs() const { return target_level_dbfs_; }
-
-  virtual float voice_probability() const {
-    return vad_.last_voice_probability();
-  }
+  virtual int target_level_dbfs() const;
+  virtual float voice_probability() const;
 
  private:
   double target_level_loudness_;