Delete deprecated AEC interfaces

They've been officially deprecated since September 4, 2018.
PSA: https://groups.google.com/forum/#!topic/discuss-webrtc/r_9n-PRUIX4

Bug: webrtc:9535
Change-Id: I294e22ae874b1edd81a0a0347755d82c5ebc61e0
Reviewed-on: https://webrtc-review.googlesource.com/c/103444
Reviewed-by: Gustaf Ullberg <gustaf@webrtc.org>
Commit-Queue: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#24971}
diff --git a/modules/audio_processing/audio_processing_impl.cc b/modules/audio_processing/audio_processing_impl.cc
index 95d36b8..b9153fa 100644
--- a/modules/audio_processing/audio_processing_impl.cc
+++ b/modules/audio_processing/audio_processing_impl.cc
@@ -24,9 +24,7 @@
 #include "modules/audio_processing/audio_buffer.h"
 #include "modules/audio_processing/common.h"
 #include "modules/audio_processing/echo_cancellation_impl.h"
-#include "modules/audio_processing/echo_cancellation_proxy.h"
 #include "modules/audio_processing/echo_control_mobile_impl.h"
-#include "modules/audio_processing/echo_control_mobile_proxy.h"
 #include "modules/audio_processing/gain_control_for_experimental_agc.h"
 #include "modules/audio_processing/gain_control_impl.h"
 #include "modules/audio_processing/gain_controller2.h"
@@ -253,8 +251,6 @@
   // Accessed externally of APM without any lock acquired.
   std::unique_ptr<EchoCancellationImpl> echo_cancellation;
   std::unique_ptr<EchoControlMobileImpl> echo_control_mobile;
-  std::unique_ptr<EchoCancellationProxy> echo_cancellation_proxy;
-  std::unique_ptr<EchoControlMobileProxy> echo_control_mobile_proxy;
   std::unique_ptr<GainControlImpl> gain_control;
   std::unique_ptr<LevelEstimatorImpl> level_estimator;
   std::unique_ptr<NoiseSuppressionImpl> noise_suppression;
@@ -398,11 +394,6 @@
         new EchoCancellationImpl(&crit_render_, &crit_capture_));
     public_submodules_->echo_control_mobile.reset(
         new EchoControlMobileImpl(&crit_render_, &crit_capture_));
-    public_submodules_->echo_cancellation_proxy.reset(new EchoCancellationProxy(
-        this, public_submodules_->echo_cancellation.get()));
-    public_submodules_->echo_control_mobile_proxy.reset(
-        new EchoControlMobileProxy(
-            this, public_submodules_->echo_control_mobile.get()));
     public_submodules_->gain_control.reset(
         new GainControlImpl(&crit_render_, &crit_capture_));
     public_submodules_->level_estimator.reset(
@@ -684,8 +675,8 @@
 
   public_submodules_->echo_cancellation->set_suppression_level(
       config.echo_canceller.legacy_moderate_suppression_level
-          ? EchoCancellation::SuppressionLevel::kModerateSuppression
-          : EchoCancellation::SuppressionLevel::kHighSuppression);
+          ? EchoCancellationImpl::SuppressionLevel::kModerateSuppression
+          : EchoCancellationImpl::SuppressionLevel::kHighSuppression);
 
   InitializeLowCutFilter();
 
@@ -1650,7 +1641,7 @@
 AudioProcessing::AudioProcessingStatistics AudioProcessingImpl::GetStatistics()
     const {
   AudioProcessingStatistics stats;
-  EchoCancellation::Metrics metrics;
+  EchoCancellationImpl::Metrics metrics;
   if (private_submodules_->echo_controller) {
     rtc::CritScope cs_capture(&crit_capture_);
     auto ec_metrics = private_submodules_->echo_controller->GetMetrics();
@@ -1686,7 +1677,7 @@
     bool has_remote_tracks) const {
   AudioProcessingStats stats;
   if (has_remote_tracks) {
-    EchoCancellation::Metrics metrics;
+    EchoCancellationImpl::Metrics metrics;
     if (private_submodules_->echo_controller) {
       rtc::CritScope cs_capture(&crit_capture_);
       auto ec_metrics = private_submodules_->echo_controller->GetMetrics();
@@ -1733,14 +1724,6 @@
   return stats;
 }
 
-EchoCancellation* AudioProcessingImpl::echo_cancellation() const {
-  return public_submodules_->echo_cancellation_proxy.get();
-}
-
-EchoControlMobile* AudioProcessingImpl::echo_control_mobile() const {
-  return public_submodules_->echo_control_mobile_proxy.get();
-}
-
 GainControl* AudioProcessingImpl::gain_control() const {
   if (constants_.use_experimental_agc) {
     return public_submodules_->gain_control_for_experimental_agc.get();