Have AUAudioInputStream::Stop() also cancel any deferred start.

media/audio/mac/audio_low_latency_input_mac.cc

Index: media/audio/mac/audio_low_latency_input_mac.cc
diff --git a/media/audio/mac/audio_low_latency_input_mac.cc b/media/audio/mac/audio_low_latency_input_mac.cc
index c347e8845cee112cbc5c6c2b97c07cc08121c60d..15640a57ca94816cdef601122bef988982cf6150 100644
--- a/media/audio/mac/audio_low_latency_input_mac.cc
+++ b/media/audio/mac/audio_low_latency_input_mac.cc
@@ -577,6 +577,7 @@ void AUAudioInputStream::Start(AudioInputCallback* callback) {
 
 void AUAudioInputStream::Stop() {
   DCHECK(thread_checker_.CalledOnValidThread());
+  deferred_start_cb_.Cancel();
   DVLOG(1) << "Stop";
   StopAgc();
   if (check_alive_timer_ != nullptr) {