Adding stats that can be used to compute output audio levels.

webrtc/voice_engine/channel_proxy.h

Index: webrtc/voice_engine/channel_proxy.h
diff --git a/webrtc/voice_engine/channel_proxy.h b/webrtc/voice_engine/channel_proxy.h
index 35d0df5360bd31faea85924cea79af622c63ac75..fee3d1a46b4c9fa010aa2bb12e29c3916016fe55 100644
--- a/webrtc/voice_engine/channel_proxy.h
+++ b/webrtc/voice_engine/channel_proxy.h
@@ -82,6 +82,9 @@ class ChannelProxy {
   virtual AudioDecodingCallStats GetDecodingCallStatistics() const;
   virtual int GetSpeechOutputLevel() const;
   virtual int GetSpeechOutputLevelFullRange() const;
+  // See description of "totalAudioEnergy" in the WebRTC stats spec.
+  virtual double GetTotalOutputEnergy() const;
+  virtual double GetTotalOutputDuration() const;
   virtual uint32_t GetDelayEstimate() const;
   virtual bool SetSendTelephoneEventPayloadType(int payload_type,
                                                 int payload_frequency);