NetEq: Convert AverageIAT from int to float calculations

webrtc/modules/audio_coding/neteq/delay_manager.h

Index: webrtc/modules/audio_coding/neteq/delay_manager.h
diff --git a/webrtc/modules/audio_coding/neteq/delay_manager.h b/webrtc/modules/audio_coding/neteq/delay_manager.h
index 2f928f175be695e54a8b8a59fbdaa979a35f3d09..78715720b896ab6e55e1eb60843ea74ebaa575cb 100644
--- a/webrtc/modules/audio_coding/neteq/delay_manager.h
+++ b/webrtc/modules/audio_coding/neteq/delay_manager.h
@@ -72,7 +72,7 @@ class DelayManager {
   // the nominal frame time, the return value is zero. A positive value
   // corresponds to packet spacing being too large, while a negative value means
   // that the packets arrive with less spacing than expected.
-  virtual int AverageIAT() const;
+  virtual double EstimatedClockDriftPpm() const;
 
   // Returns true if peak-mode is active. That is, delay peaks were observed
   // recently. This method simply asks for the same information from the