Changed name for the upcoming AEC from NextGenerationAec to AEC3.

BUG=webrtc:5201

Review URL: https://codereview.webrtc.org/1763703002

Cr-Commit-Position: refs/heads/master@{#11895}
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index 8af5f53..6fb10c6 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -73,10 +73,10 @@
 // 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;
+struct EchoCanceller3 {
+  EchoCanceller3() : enabled(false) {}
+  explicit EchoCanceller3(bool enabled) : enabled(enabled) {}
+  static const ConfigOptionID identifier = ConfigOptionID::kEchoCanceller3;
   bool enabled;
 };