Updated comments for unit tests to validate iOS audio session isInterrupted flag does not get reset…

webrtc/modules/audio_device/ios/audio_device_unittest_ios.mm

Index: webrtc/modules/audio_device/ios/audio_device_unittest_ios.mm
diff --git a/webrtc/modules/audio_device/ios/audio_device_unittest_ios.mm b/webrtc/modules/audio_device/ios/audio_device_unittest_ios.mm
index 82f4426482ad3f93ecdafe3600d1f3335a043d80..d7eed0f870aa5530a142e8b0e9954dc36b3f43d9 100644
--- a/webrtc/modules/audio_device/ios/audio_device_unittest_ios.mm
+++ b/webrtc/modules/audio_device/ios/audio_device_unittest_ios.mm
@@ -825,6 +825,18 @@ TEST_F(AudioDeviceTest, DISABLED_MeasureLoopbackLatency) {
   latency_audio_stream->PrintResults();
 }
 
+// Verifies that the AudioDeviceIOS is_interrupted_ flag is reset correctly

[tkchin_webrtc, 2017/05/17 18:15:26]

I think this needs some information about when AudioDeviceIOS subscribes to
notifications from RTCAudioSession.

It's not so much that RTCAudioSession can't notify the audio device - it's that
the audio device is choosing not to listen when playback or recording is not set
up.

+// after an iOS AVAudioSessionInterruptionTypeEnded notification event.
+// When AudioDeviceIOS is interrupted, is_interrupted_ is set to true.
+// When the audio device is stopped, the AudioDeviceIOS's
+// audio_session_observer_ is removed from RTCAudioSession's delegate list.
+// Then when the iOS AVAudioSessionInterruptionTypeEnded notification is
+// received by RTCAudioSession, RTCAudioSession can't propagate the event
+// back to AudioDeviceIOS as AudioDeviceIOS's audio_session_observer_ is no
+// longer in RTCAudioSession's delegate list.
+// The fix is to set AudioDeviceIOS's is_interrupted_ flag to RTCAudioSession's
+// isInterrupted flag when AudioDeviceIOS is initialized the next time audio
+// is to be started.
 TEST_F(AudioDeviceTest, testInterruptedAudioSession) {
   RTCAudioSession *session = [RTCAudioSession sharedInstance];
   std::unique_ptr<webrtc::AudioDeviceIOS> audio_device;