Disables AudioDeviceTest.StartStopPlayout on iOS

webrtc/modules/audio_device/ios/audio_device_unittest_ios.cc

Index: webrtc/modules/audio_device/ios/audio_device_unittest_ios.cc
diff --git a/webrtc/modules/audio_device/ios/audio_device_unittest_ios.cc b/webrtc/modules/audio_device/ios/audio_device_unittest_ios.cc
index c2821815bab593548f1cde5fdb92a338b58fd3e6..1b7ff5780f9177be6132f184b0b6e4713e904d24 100644
--- a/webrtc/modules/audio_device/ios/audio_device_unittest_ios.cc
+++ b/webrtc/modules/audio_device/ios/audio_device_unittest_ios.cc
@@ -588,7 +588,8 @@ TEST_F(AudioDeviceTest, InitTerminate) {
 
 // Tests that playout can be initiated, started and stopped. No audio callback
 // is registered in this test.
-TEST_F(AudioDeviceTest, StartStopPlayout) {
+// Failing when running on real iOS devices: bugs.webrtc.org/6889.
+TEST_F(AudioDeviceTest, DISABLED_StartStopPlayout) {
   StartPlayout();
   StopPlayout();
   StartPlayout();