AirPods removed from ears should not disturb and ongoing video call

https://bugs.webkit.org/show_bug.cgi?id=264334
rdar://116091083

Reviewed by Eric Carlson.

When AirPods are removed from ears, AirPods are disappearing from the list of existing devices.
Before the patch, it would trigger capture failure. But web pages do not handle well capture failure.
To help web pages, if capturing with the default microphone and the microphone is disappearing, we are now
migrating to the new default microphone.
We make sure to trigger a configurationchange event on the MediaStreamTrack, which exposes the change to the web page.

* Source/WebCore/platform/mediastream/mac/BaseAudioSharedUnit.cpp:
(WebCore::BaseAudioSharedUnit::setCaptureDevice):
(WebCore::BaseAudioSharedUnit::devicesChanged):
* Source/WebCore/platform/mediastream/mac/BaseAudioSharedUnit.h:
(WebCore::BaseAudioSharedUnit::migrateToNewDefaultDevice):
* Source/WebCore/platform/mediastream/mac/CoreAudioSharedUnit.cpp:
(WebCore::CoreAudioSharedUnit::migrateToNewDefaultDevice):
* Source/WebCore/platform/mediastream/mac/CoreAudioSharedUnit.h:

Canonical link: https://commits.webkit.org/270433@main

Source/WebCore/platform/mediastream/mac/BaseAudioSharedUnit.cpp

@@ -153,6 +153,9 @@ void BaseAudioSharedUnit::setCaptureDevice(String&& persistentID, uint32_t captu
     bool hasChanged = this->persistentID() != persistentID || this->captureDeviceID() != captureDeviceID;
     m_capturingDevice = { WTFMove(persistentID), captureDeviceID };
 
+    auto devices = RealtimeMediaSourceCenter::singleton().audioCaptureFactory().audioCaptureDeviceManager().captureDevices();
+    m_isCapturingWithDefaultMicrophone = devices.size() && devices[0].persistentId() == m_capturingDevice->first;
+
     if (hasChanged)
         captureDeviceChanged();
 }
@@ -174,6 +177,11 @@ void BaseAudioSharedUnit::devicesChanged()
         return;
     }
 
+    if (devices.size() && m_isCapturingWithDefaultMicrophone && migrateToNewDefaultDevice(devices[0])) {
+        RELEASE_LOG_ERROR(WebRTC, "BaseAudioSharedUnit::devicesChanged - migrating to new default device");
+        return;
+    }
+
     RELEASE_LOG_ERROR(WebRTC, "BaseAudioSharedUnit::devicesChanged - failing capture, capturing device is missing");
     captureFailed();
 }

Source/WebCore/platform/mediastream/mac/BaseAudioSharedUnit.h

@@ -116,6 +116,7 @@ class BaseAudioSharedUnit : public RealtimeMediaSourceCenter::Observer {
 
     virtual void isProducingMicrophoneSamplesChanged() { }
     virtual void validateOutputDevice(uint32_t /* currentOutputDeviceID */) { }
+    virtual bool migrateToNewDefaultDevice(const CaptureDevice&) { return false; }
 
 private:
     OSStatus startUnit();
@@ -140,6 +141,7 @@ class BaseAudioSharedUnit : public RealtimeMediaSourceCenter::Observer {
     Vector<CheckedPtr<CoreAudioCaptureSource>> m_audioThreadClients WTF_GUARDED_BY_LOCK(m_audioThreadClientsLock);
     Lock m_audioThreadClientsLock;
 
+    bool m_isCapturingWithDefaultMicrophone { false };
     bool m_isProducingMicrophoneSamples { true };
     Vector<Function<void()>> m_whenNotRunningCallbacks;
 };

Source/WebCore/platform/mediastream/mac/CoreAudioSharedUnit.cpp

@@ -50,6 +50,11 @@
 #include "MediaCaptureStatusBarManager.h"
 #endif
 
+#if PLATFORM(MAC)
+#include "CoreAudioCaptureDevice.h"
+#include "CoreAudioCaptureDeviceManager.h"
+#endif
+
 #include <pal/cf/AudioToolboxSoftLink.h>
 #include <pal/cf/CoreMediaSoftLink.h>
 
@@ -663,6 +668,22 @@ void CoreAudioSharedUnit::validateOutputDevice(uint32_t currentOutputDeviceID)
 #endif
 }
 
+#if PLATFORM(MAC)
+bool CoreAudioSharedUnit::migrateToNewDefaultDevice(const CaptureDevice& captureDevice)
+{
+    auto newDefaultDevicePersistentId = captureDevice.persistentId();
+    auto device = CoreAudioCaptureDeviceManager::singleton().coreAudioDeviceWithUID(newDefaultDevicePersistentId);
+    if (!device)
+        return false;
+
+    // We were capturing with the default device which disappeared, let's move capture to the new default device.
+    setCaptureDevice(WTFMove(newDefaultDevicePersistentId), device->deviceID());
+    handleNewCurrentMicrophoneDevice(WTFMove(*device));
+    return true;
+}
+#endif
+
+
 void CoreAudioSharedUnit::verifyIsCapturing()
 {
     if (m_microphoneProcsCalledLastTime != m_microphoneProcsCalled) {

Source/WebCore/platform/mediastream/mac/CoreAudioSharedUnit.h

@@ -118,6 +118,9 @@ class CoreAudioSharedUnit final : public BaseAudioSharedUnit {
     bool isProducingData() const final { return m_ioUnitStarted; }
     void isProducingMicrophoneSamplesChanged() final;
     void validateOutputDevice(uint32_t deviceID) final;
+#if PLATFORM(MAC)
+    bool migrateToNewDefaultDevice(const CaptureDevice&) final;
+#endif
     int actualSampleRate() const final;
     void resetSampleRate();