Introduced the new parameter setting scheme for activating the high-pass filter in APM

webrtc/modules/audio_processing/audio_processing_impl.h

Index: webrtc/modules/audio_processing/audio_processing_impl.h
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.h b/webrtc/modules/audio_processing/audio_processing_impl.h
index d6af64d22f08dffdf62aa8c198429e5236e96f52..a40cde3e55cfc7052064b400b559cb8c18110bd4 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.h
+++ b/webrtc/modules/audio_processing/audio_processing_impl.h
@@ -124,11 +124,16 @@ class AudioProcessingImpl : public AudioProcessing {
   EchoCancellation* echo_cancellation() const override;
   EchoControlMobile* echo_control_mobile() const override;
   GainControl* gain_control() const override;
+  // TODO(peah): Deprecate this API call.
   HighPassFilter* high_pass_filter() const override;
   LevelEstimator* level_estimator() const override;
   NoiseSuppression* noise_suppression() const override;
   VoiceDetection* voice_detection() const override;
 
+  // TODO(peah): Remove when the HighPassFilter interface has been removed.
+  void EnableHighPassFilter(bool enable);

[the sun, 2016/10/26 09:06:43]

How about you simply expose a "const AudioProcessing::Config& config() const;"
method and use that +ApplyConfig() in you HPFImpl? I think it will scale better
when you update the other submodule APIs.

[peah-webrtc, 2016/10/28 05:50:28]

Great suggestion! 
Done.

+  bool IsHighPassFilterEnabled();
+
  protected:
   // Overridden in a mock.
   virtual int InitializeLocked()
@@ -234,6 +239,7 @@ class AudioProcessingImpl : public AudioProcessing {
   int InitializeLocked(const ProcessingConfig& config)
       EXCLUSIVE_LOCKS_REQUIRED(crit_render_, crit_capture_);
   void InitializeLevelController() EXCLUSIVE_LOCKS_REQUIRED(crit_capture_);
+  void InitializeHighPassFilter() EXCLUSIVE_LOCKS_REQUIRED(crit_capture_);
 
   void EmptyQueuedRenderAudio();
   void AllocateRenderQueue()