Moving iOS Audio Device to sdk.

This change forks the existing iOS audio device module and audio device
from modules/audio_device/ into sdk/objc/Framework. It also updates
RTCPeerConnectionFactory to use the forked implementation.

The unit tests are re-implemented as XCTests.

(was: https://webrtc-review.googlesource.com/c/src/+/67300)

Bug: webrtc:9120
Change-Id: I07340505137b16c2dd487569ad0112f984557bba
Reviewed-on: https://webrtc-review.googlesource.com/75125
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Peter Hanspers <peterhanspers@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23208}

sdk/objc/Framework/Native/api/audio_device_module.h

@@ -0,0 +1,24 @@
+/*
+ *  Copyright 2018 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.
+ */
+
+#ifndef SDK_OBJC_FRAMEWORK_NATIVE_API_AUDIO_DEVICE_MODULE_H_
+#define SDK_OBJC_FRAMEWORK_NATIVE_API_AUDIO_DEVICE_MODULE_H_
+
+#include <memory>
+
+#include "modules/audio_device/include/audio_device.h"
+
+namespace webrtc {
+
+rtc::scoped_refptr<AudioDeviceModule> CreateAudioDeviceModule();
+
+}  // namespace webrtc
+
+#endif // SDK_OBJC_FRAMEWORK_NATIVE_API_AUDIO_DEVICE_MODULE_H_

sdk/objc/Framework/Native/api/audio_device_module.mm

@@ -0,0 +1,30 @@
+/*
+ *  Copyright 2018 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 "audio_device_module.h"
+
+#include "rtc_base/logging.h"
+#include "rtc_base/refcountedobject.h"
+
+#include "sdk/objc/Framework/Native/src/audio/audio_device_module_ios.h"
+
+namespace webrtc {
+
+rtc::scoped_refptr<AudioDeviceModule> CreateAudioDeviceModule() {
+  RTC_LOG(INFO) << __FUNCTION__;
+#if defined(WEBRTC_IOS)
+  return new rtc::RefCountedObject<ios_adm::AudioDeviceModuleIOS>();
+#else
+  RTC_LOG(LERROR)
+      << "current platform is not supported => this module will self destruct!";
+  return nullptr;
+#endif
+}
+}