Move the aec_rdft* files to a more proper place beneath APM and make them thread-safe.

webrtc/modules/audio_processing/level_controller/signal_classifier.cc

Index: webrtc/modules/audio_processing/level_controller/signal_classifier.cc
diff --git a/webrtc/modules/audio_processing/level_controller/signal_classifier.cc b/webrtc/modules/audio_processing/level_controller/signal_classifier.cc
index c9a07e754d8f0e58c3a1cdfcb59600edf6db7d92..dd67737403aba12e9cdf089c4bef463dac53d4a5 100644
--- a/webrtc/modules/audio_processing/level_controller/signal_classifier.cc
+++ b/webrtc/modules/audio_processing/level_controller/signal_classifier.cc
@@ -16,7 +16,6 @@
 
 #include "webrtc/base/array_view.h"
 #include "webrtc/base/constructormagic.h"
-#include "webrtc/modules/audio_processing/aec/aec_rdft.h"
 #include "webrtc/modules/audio_processing/audio_buffer.h"
 #include "webrtc/modules/audio_processing/level_controller/down_sampler.h"
 #include "webrtc/modules/audio_processing/level_controller/noise_spectrum_estimator.h"
@@ -35,13 +34,14 @@ void RemoveDcLevel(rtc::ArrayView<float> x) {
   }
 }
 
-void PowerSpectrum(rtc::ArrayView<const float> x,
+void PowerSpectrum(const OouraFft* ooura_fft,
+                   rtc::ArrayView<const float> x,
                    rtc::ArrayView<float> spectrum) {
   RTC_DCHECK_EQ(65u, spectrum.size());
   RTC_DCHECK_EQ(128u, x.size());
   float X[128];
   std::copy(x.data(), x.data() + x.size(), X);
-  aec_rdft_forward_128(X);
+  ooura_fft->Fft(X);
 
   float* X_p = X;
   RTC_DCHECK_EQ(X_p, &X[0]);
@@ -118,7 +118,6 @@ SignalClassifier::SignalClassifier(ApmDataDumper* data_dumper)
 SignalClassifier::~SignalClassifier() {}
 
 void SignalClassifier::Initialize(int sample_rate_hz) {
-  aec_rdft_init();
   down_sampler_.Initialize(sample_rate_hz);
   noise_spectrum_estimator_.Initialize();
   frame_extender_.reset(new FrameExtender(80, 128));
@@ -141,7 +140,7 @@ void SignalClassifier::Analyze(const AudioBuffer& audio,
   frame_extender_->ExtendFrame(downsampled_frame, extended_frame);
   RemoveDcLevel(extended_frame);
   float signal_spectrum[65];
-  PowerSpectrum(extended_frame, signal_spectrum);
+  PowerSpectrum(&ooura_fft_, extended_frame, signal_spectrum);
 
   // Classify the signal based on the estimate of the noise spectrum and the
   // signal spectrum estimate.