Add helper to inject custom implementation of audio processing as factory

This would simplify migrating from PeerConnectionFactoryDependencies::audio_processing
for users who use own implementation of the AudioProcessing

Bug: webrtc:369904700
Change-Id: Id05f7280fd01a3e8fd4953f1b24b2467335ab065
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/366120
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43273}

api/audio/BUILD.gn

@@ -167,11 +167,16 @@ rtc_source_set("echo_detector_creator") {
 if (rtc_include_tests) {
   rtc_library("audio_api_unittests") {
     testonly = true
-    sources = [ "builtin_audio_processing_factory_unittest.cc" ]
+    sources = [
+      "audio_processing_unittest.cc",
+      "builtin_audio_processing_factory_unittest.cc",
+    ]
     deps = [
       ":audio_processing",
       ":builtin_audio_processing_factory",
+      "..:make_ref_counted",
       "..:scoped_refptr",
+      "../../modules/audio_processing:mocks",
       "../../test:test_support",
       "../environment",
       "../environment:environment_factory",

api/audio/audio_processing.cc

@@ -9,8 +9,14 @@
  */
 
 #include "api/audio/audio_processing.h"
-#include <string>
 
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "absl/base/nullability.h"
+#include "api/environment/environment.h"
+#include "api/scoped_refptr.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/strings/string_builder.h"
 
@@ -208,4 +214,24 @@ std::string AudioProcessing::Config::ToString() const {
   return builder.str();
 }
 
+absl::Nonnull<std::unique_ptr<AudioProcessingFactory>> CustomAudioProcessing(
+    absl::Nonnull<scoped_refptr<AudioProcessing>> audio_processing) {
+  class Factory : public AudioProcessingFactory {
+   public:
+    explicit Factory(absl::Nonnull<scoped_refptr<AudioProcessing>> ap)
+        : ap_(std::move(ap)) {}
+
+    absl::Nullable<scoped_refptr<AudioProcessing>> Create(
+        const Environment& /*env*/) override {
+      return ap_;
+    }
+
+   private:
+    absl::Nonnull<scoped_refptr<AudioProcessing>> ap_;
+  };
+
+  RTC_CHECK(audio_processing);
+  return std::make_unique<Factory>(std::move(audio_processing));
+}
+
 }  // namespace webrtc

api/audio/audio_processing.h

@@ -742,6 +742,14 @@ class AudioProcessingFactory {
       const Environment& env) = 0;
 };
 
+// Returns factory that always returns the same `audio_processing` ignoring the
+// extra construction parameter `env`.
+// nullptr `audio_processing` is not supported as in some scenarios that imply
+// no audio processing, while in others - default builtin audio processing.
+// Callers should be explicit which of these two behaviors they want.
+absl::Nonnull<std::unique_ptr<AudioProcessingFactory>> CustomAudioProcessing(
+    absl::Nonnull<scoped_refptr<AudioProcessing>> audio_processing);
+
 // Experimental interface for a custom analysis submodule.
 class CustomAudioAnalyzer {
  public:

api/audio/audio_processing_unittest.cc

@@ -0,0 +1,47 @@
+/*
+ *  Copyright (c) 2024 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.
+ */
+
+#include "api/audio/audio_processing.h"
+
+#include <memory>
+
+#include "api/environment/environment_factory.h"
+#include "api/make_ref_counted.h"
+#include "api/scoped_refptr.h"
+#include "modules/audio_processing/include/mock_audio_processing.h"
+#include "test/gmock.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+
+using ::testing::_;
+using ::testing::NotNull;
+
+TEST(CustomAudioProcessingTest, ReturnsTheSameAudioProcessing) {
+  scoped_refptr<AudioProcessing> ap =
+      make_ref_counted<test::MockAudioProcessing>();
+
+  std::unique_ptr<AudioProcessingFactory> factory = CustomAudioProcessing(ap);
+
+  ASSERT_THAT(factory, NotNull());
+  EXPECT_EQ(factory->Create(CreateEnvironment()), ap);
+  EXPECT_EQ(factory->Create(CreateEnvironment()), ap);
+}
+
+#if GTEST_HAS_DEATH_TEST
+TEST(CustomAudioProcessingTest, NullptrAudioProcessingIsUnsupported) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnonnull"
+  EXPECT_DEATH(CustomAudioProcessing(nullptr), _);
+#pragma clang diagnostic pop
+}
+#endif
+
+}  // namespace webrtc

api/create_peerconnection_factory.cc

@@ -58,8 +58,9 @@ rtc::scoped_refptr<PeerConnectionFactoryInterface> CreatePeerConnectionFactory(
   dependencies.audio_encoder_factory = std::move(audio_encoder_factory);
   dependencies.audio_decoder_factory = std::move(audio_decoder_factory);
   dependencies.audio_frame_processor = std::move(audio_frame_processor);
-  if (audio_processing) {
-    dependencies.audio_processing = std::move(audio_processing);
+  if (audio_processing != nullptr) {
+    dependencies.audio_processing_factory =
+        CustomAudioProcessing(std::move(audio_processing));
   } else {
 #ifndef WEBRTC_EXCLUDE_AUDIO_PROCESSING_MODULE
     dependencies.audio_processing_factory =

test/pc/e2e/BUILD.gn

@@ -108,6 +108,7 @@ if (!build_with_chromium) {
         "../../../api:scoped_refptr",
         "../../../api:time_controller",
         "../../../api/audio:audio_device",
+        "../../../api/audio:audio_processing",
         "../../../api/rtc_event_log:rtc_event_log_factory",
         "../../../api/task_queue",
         "../../../api/task_queue:default_task_queue_factory",

test/pc/e2e/test_peer_factory.cc

@@ -18,6 +18,7 @@
 #include "absl/memory/memory.h"
 #include "absl/strings/string_view.h"
 #include "api/audio/audio_device.h"
+#include "api/audio/audio_processing.h"
 #include "api/peer_connection_interface.h"
 #include "api/rtc_event_log/rtc_event_log_factory.h"
 #include "api/scoped_refptr.h"
@@ -226,7 +227,10 @@ PeerConnectionFactoryDependencies CreatePCFDependencies(
 
   // Media dependencies
   pcf_deps.adm = std::move(audio_device_module);
-  pcf_deps.audio_processing = pcf_dependencies->audio_processing;
+  if (pcf_dependencies->audio_processing != nullptr) {
+    pcf_deps.audio_processing_factory =
+        CustomAudioProcessing(pcf_dependencies->audio_processing);
+  }
   pcf_deps.audio_mixer = pcf_dependencies->audio_mixer;
   pcf_deps.video_encoder_factory =
       std::move(pcf_dependencies->video_encoder_factory);