Boilerplate code addition in order to be able to test upcoming AEC additions

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 138259cf9600a56a5028232f1270b617ca4dfa8c..2311c65e5495bb65d87a084e05c6cf55b0e8d3b2 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -69,6 +69,17 @@ struct ExtendedFilter {
   bool enabled;
 };
 
+// Enables the next generation AEC functionality. This feature replaces the
+// standard methods for echo removal in the AEC. This configuration only applies
+// to EchoCancellation and not EchoControlMobile. It can be set in the
+// constructor or using AudioProcessing::SetExtraOptions().
+struct NextGenerationAec {
+  NextGenerationAec() : enabled(false) {}
+  explicit NextGenerationAec(bool enabled) : enabled(enabled) {}
+  static const ConfigOptionID identifier = ConfigOptionID::kNextGenerationAec;
+  bool enabled;
+};
+
 // Enables delay-agnostic echo cancellation. This feature relies on internally
 // estimated delays between the process and reverse streams, thus not relying
 // on reported system delays. This configuration only applies to