Disable AudioDeviceTest.StartStopRecording on iOS

BUG=webrtc:7888
TBR=kjellander

Review-Url: https://codereview.webrtc.org/2963283002
Cr-Commit-Position: refs/heads/master@{#18853}
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 fd669a9..a82c111 100644
--- a/webrtc/modules/audio_device/ios/audio_device_unittest_ios.mm
+++ b/webrtc/modules/audio_device/ios/audio_device_unittest_ios.mm
@@ -602,7 +602,10 @@
 
 // Tests that recording can be initiated, started and stopped. No audio callback
 // is registered in this test.
-TEST_F(AudioDeviceTest, StartStopRecording) {
+// Can sometimes fail when running on real devices: bugs.webrtc.org/7888.
+TEST_F(AudioDeviceTest, DISABLED_StartStopRecording) {
+  StartRecording();
+  StopRecording();
   StartRecording();
   StopRecording();
 }