Enable residual echo detector on mobile platforms.

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 d1a711dfa6a3d38f02d87622ee07849c5db43f85..1b93cc0a5c495f71f8ca5d2c75ea6c8e39924fbd 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -253,11 +253,7 @@ class AudioProcessing {
       float initial_peak_level_dbfs = -6.0206f;
     } level_controller;
     struct ResidualEchoDetector {
-#if defined(WEBRTC_ANDROID) || defined(WEBRTC_IOS)
-      bool enabled = false;
-#else
       bool enabled = true;
-#endif
     } residual_echo_detector;
 
     struct HighPassFilter {