diff --git a/modules/audio_processing/include/audio_processing.h b/modules/audio_processing/include/audio_processing.h
index bf9cab7147..7452c3a4ba 100644
--- a/modules/audio_processing/include/audio_processing.h
+++ b/modules/audio_processing/include/audio_processing.h
@@ -252,6 +252,12 @@ class AudioProcessing : public rtc::RefCountInterface {
   // by changing the default values in the AudioProcessing::Config struct.
   // The config is applied by passing the struct to the ApplyConfig method.
   struct Config {
+    // TODO(bugs.webrtc.org/9535): Currently unused. Use this to determine AEC.
+    struct EchoCanceller {
+      bool enabled = false;
+      bool mobile_mode = false;
+    } echo_canceller;
+
     struct ResidualEchoDetector {
       bool enabled = true;
     } residual_echo_detector;