Revert "Remove the HighPassFilter interface"

This reverts commit e2405c1a823f3baf90a9c72f2e058f91eb659c20.

Reason for revert: Breaks Chrome compile: https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8932502586827763408/+/steps/compile__with_patch_/0/stdout 
Original change's description:
> Remove the HighPassFilter interface
> 
> The functionality remains unaffected.
> Filter toggling is still available via webrtc::AudioProcessing::Config.
> Example:
> webrtc::AudioProcessing::Config config = apm.GetConfig();
> // Read settings
> if (config.high_pass_filter.enabled) { ... }
> // Apply setting
> config.high_pass_filter.enabled = true;
> apm.ApplyConfig();
> 
> Bug: webrtc:9535
> Change-Id: Ib4c4b04078bbb490ebdab9721b8c7811d73777a8
> Reviewed-on: https://webrtc-review.googlesource.com/c/102541
> Commit-Queue: Sam Zackrisson <saza@webrtc.org>
> Reviewed-by: Fredrik Solenberg <solenberg@webrtc.org>
> Reviewed-by: Per Åhgren <peah@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#25198}

TBR=solenberg@webrtc.org,saza@webrtc.org,peah@webrtc.org

Change-Id: Ieb34d5c573c4ab22eefbb54aeaa2f72844740b89
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:9535
Reviewed-on: https://webrtc-review.googlesource.com/c/106421
Reviewed-by: Niklas Enbom <niklas.enbom@webrtc.org>
Commit-Queue: Niklas Enbom <niklas.enbom@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25215}

media/engine/apm_helpers_unittest.cc

@@ -164,4 +164,11 @@ TEST(ApmHelpersTest, TypingDetectionStatus_EnableDisable) {
   EXPECT_EQ(VoiceDetection::kVeryLowLikelihood, vd->likelihood());
   EXPECT_FALSE(vd->is_enabled());
 }
+
+// TODO(solenberg): Move this test to a better place - added here for the sake
+// of duplicating all relevant tests from audio_processing_test.cc.
+TEST(ApmHelpersTest, HighPassFilter_DefaultMode) {
+  TestHelper helper;
+  EXPECT_FALSE(helper.apm()->high_pass_filter()->is_enabled());
+}
 }  // namespace webrtc

modules/audio_processing/audio_processing_impl.cc

@@ -115,6 +115,29 @@ static const size_t kMaxAllowedValuesOfSamplesPerFrame = 480;
 // TODO(peah): Decrease this once we properly handle hugely unbalanced
 // reverse and forward call numbers.
 static const size_t kMaxNumFramesToBuffer = 100;
+
+class HighPassFilterImpl : public HighPassFilter {
+ public:
+  explicit HighPassFilterImpl(AudioProcessingImpl* apm) : apm_(apm) {}
+  ~HighPassFilterImpl() override = default;
+
+  // HighPassFilter implementation.
+  int Enable(bool enable) override {
+    apm_->MutateConfig([enable](AudioProcessing::Config* config) {
+      config->high_pass_filter.enabled = enable;
+    });
+
+    return AudioProcessing::kNoError;
+  }
+
+  bool is_enabled() const override {
+    return apm_->GetConfig().high_pass_filter.enabled;
+  }
+
+ private:
+  AudioProcessingImpl* apm_;
+  RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(HighPassFilterImpl);
+};
 }  // namespace
 
 // Throughout webrtc, it's assumed that success is represented by zero.
@@ -329,6 +352,7 @@ AudioProcessingImpl::AudioProcessingImpl(
       render_runtime_settings_(kRuntimeSettingQueueSize),
       capture_runtime_settings_enqueuer_(&capture_runtime_settings_),
       render_runtime_settings_enqueuer_(&render_runtime_settings_),
+      high_pass_filter_impl_(new HighPassFilterImpl(this)),
       echo_control_factory_(std::move(echo_control_factory)),
       submodule_states_(!!capture_post_processor,
                         !!render_pre_processor,
@@ -1703,6 +1727,10 @@ GainControl* AudioProcessingImpl::gain_control() const {
   return public_submodules_->gain_control.get();
 }
 
+HighPassFilter* AudioProcessingImpl::high_pass_filter() const {
+  return high_pass_filter_impl_.get();
+}
+
 LevelEstimator* AudioProcessingImpl::level_estimator() const {
   return public_submodules_->level_estimator.get();
 }

modules/audio_processing/audio_processing_impl.h

@@ -118,6 +118,8 @@ class AudioProcessingImpl : public AudioProcessing {
   // created only once in a single-treaded manner
   // during APM creation).
   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;
@@ -162,6 +164,9 @@ class AudioProcessingImpl : public AudioProcessing {
   RuntimeSettingEnqueuer capture_runtime_settings_enqueuer_;
   RuntimeSettingEnqueuer render_runtime_settings_enqueuer_;
 
+  // Submodule interface implementations.
+  std::unique_ptr<HighPassFilter> high_pass_filter_impl_;
+
   // EchoControl factory.
   std::unique_ptr<EchoControlFactory> echo_control_factory_;
 

modules/audio_processing/audio_processing_unittest.cc

@@ -1278,6 +1278,7 @@ TEST_F(ApmTest, AllProcessingDisabledByDefault) {
   EXPECT_FALSE(config.echo_canceller.enabled);
   EXPECT_FALSE(config.high_pass_filter.enabled);
   EXPECT_FALSE(apm_->gain_control()->is_enabled());
+  EXPECT_FALSE(apm_->high_pass_filter()->is_enabled());
   EXPECT_FALSE(apm_->level_estimator()->is_enabled());
   EXPECT_FALSE(apm_->noise_suppression()->is_enabled());
   EXPECT_FALSE(apm_->voice_detection()->is_enabled());

modules/audio_processing/include/audio_processing.h

@@ -49,6 +49,7 @@ class ProcessingConfig;
 
 class EchoDetector;
 class GainControl;
+class HighPassFilter;
 class LevelEstimator;
 class NoiseSuppression;
 class CustomAudioAnalyzer;
@@ -597,6 +598,8 @@ class AudioProcessing : public rtc::RefCountInterface {
   // NULL. The pointers will be valid for the lifetime of the APM instance.
   // The memory for these objects is entirely managed internally.
   virtual GainControl* gain_control() const = 0;
+  // TODO(peah): Deprecate this API call.
+  virtual HighPassFilter* high_pass_filter() const = 0;
   virtual LevelEstimator* level_estimator() const = 0;
   virtual NoiseSuppression* noise_suppression() const = 0;
   virtual VoiceDetection* voice_detection() const = 0;
@@ -786,6 +789,17 @@ class ProcessingConfig {
   StreamConfig streams[StreamName::kNumStreamNames];
 };
 
+// TODO(peah): Remove this interface.
+// A filtering component which removes DC offset and low-frequency noise.
+// Recommended to be enabled on the client-side.
+class HighPassFilter {
+ public:
+  virtual int Enable(bool enable) = 0;
+  virtual bool is_enabled() const = 0;
+
+  virtual ~HighPassFilter() {}
+};
+
 // An estimation component used to retrieve level metrics.
 class LevelEstimator {
  public:

modules/audio_processing/include/mock_audio_processing.h

@@ -42,6 +42,13 @@ class MockGainControl : public GainControl {
   MOCK_CONST_METHOD0(stream_is_saturated, bool());
 };
 
+class MockHighPassFilter : public HighPassFilter {
+ public:
+  virtual ~MockHighPassFilter() {}
+  MOCK_METHOD1(Enable, int(bool enable));
+  MOCK_CONST_METHOD0(is_enabled, bool());
+};
+
 class MockLevelEstimator : public LevelEstimator {
  public:
   virtual ~MockLevelEstimator() {}
@@ -107,6 +114,7 @@ class MockAudioProcessing : public testing::NiceMock<AudioProcessing> {
  public:
   MockAudioProcessing()
       : gain_control_(new testing::NiceMock<MockGainControl>()),
+        high_pass_filter_(new testing::NiceMock<MockHighPassFilter>()),
         level_estimator_(new testing::NiceMock<MockLevelEstimator>()),
         noise_suppression_(new testing::NiceMock<MockNoiseSuppression>()),
         voice_detection_(new testing::NiceMock<MockVoiceDetection>()) {}
@@ -175,6 +183,9 @@ class MockAudioProcessing : public testing::NiceMock<AudioProcessing> {
   MOCK_CONST_METHOD0(GetStatistics, AudioProcessingStatistics());
   MOCK_CONST_METHOD1(GetStatistics, AudioProcessingStats(bool));
   virtual MockGainControl* gain_control() const { return gain_control_.get(); }
+  virtual MockHighPassFilter* high_pass_filter() const {
+    return high_pass_filter_.get();
+  }
   virtual MockLevelEstimator* level_estimator() const {
     return level_estimator_.get();
   }
@@ -189,6 +200,7 @@ class MockAudioProcessing : public testing::NiceMock<AudioProcessing> {
 
  private:
   std::unique_ptr<MockGainControl> gain_control_;
+  std::unique_ptr<MockHighPassFilter> high_pass_filter_;
   std::unique_ptr<MockLevelEstimator> level_estimator_;
   std::unique_ptr<MockNoiseSuppression> noise_suppression_;
   std::unique_ptr<MockVoiceDetection> voice_detection_;