Re-land r9378 "Rename APM Config DelayCorrection to ExtendedFilter"

webrtc/modules/audio_processing/include/audio_processing.h

Index: webrtc/modules/audio_processing/include/audio_processing.h
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index 8c3436d5398b770fb03922b10030372fe4833922..a4dd0495c21cedd1ad7224fb9be352094f13870d 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -37,10 +37,10 @@ class LevelEstimator;
 class NoiseSuppression;
 class VoiceDetection;
 
-// Use to enable the delay correction feature. This now engages an extended
-// filter mode in the AEC, along with robustness measures around the reported
-// system delays. It comes with a significant increase in AEC complexity, but is
-// much more robust to unreliable reported delays.
+// Use to enable the extended filter mode in the AEC, along with robustness
+// measures around the reported system delays. It comes with a significant
+// increase in AEC complexity, but is much more robust to unreliable reported
+// delays.
 //
 // Detailed changes to the algorithm:
 // - The filter length is changed from 48 to 128 ms. This comes with tuning of
@@ -54,11 +54,19 @@ class VoiceDetection;
 //   the delay difference more heavily, and back off from the difference more.
 //   Adjustments force a readaptation of the filter, so they should be avoided
 //   except when really necessary.
+// TODO(henrik.lundin): Remove DelayCorrection once ExtendedFilter has
+// propagated through to all channels
+// (https://code.google.com/p/webrtc/issues/detail?id=4696).
 struct DelayCorrection {
   DelayCorrection() : enabled(false) {}
   explicit DelayCorrection(bool enabled) : enabled(enabled) {}
   bool enabled;
 };
+struct ExtendedFilter {
+  ExtendedFilter() : enabled(false) {}
+  explicit ExtendedFilter(bool enabled) : enabled(enabled) {}
+  bool enabled;
+};
 
 // Use to disable the reported system delays. By disabling the reported system
 // delays the echo cancellation algorithm assumes the process and reverse