Enable residual echo detector on mobile platforms.

webrtc/modules/audio_processing/include/audio_processing.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 235 matching lines @@
   struct Config {
     struct LevelController {
       bool enabled = false;
 
       // Sets the initial peak level to use inside the level controller in order
       // to compute the signal gain. The unit for the peak level is dBFS and
       // the allowed range is [-100, 0].
       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 {
       bool enabled = false;
     } high_pass_filter;
 
     // Enables the next generation AEC functionality. This feature replaces the
     // standard methods for echo removal in the AEC.
     // The functionality is not yet activated in the code and turning this on
     // does not yet have the desired behavior.
@@ skipping 807 matching lines @@
   // This does not impact the size of frames passed to |ProcessStream()|.
   virtual int set_frame_size_ms(int size) = 0;
   virtual int frame_size_ms() const = 0;
 
  protected:
   virtual ~VoiceDetection() {}
 };
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_INCLUDE_AUDIO_PROCESSING_H_