Fixes crash in AudioManagerMac at shutdown

media/audio/mac/audio_manager_mac.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/audio/mac/audio_manager_mac.h"
 
 #include <algorithm>
 #include <limits>
 #include <vector>
 
@@ skipping 372 matching lines @@
   // We are now in shutdown mode. This flag disables MaybeChangeBufferSize()
   // and IncreaseIOBufferSizeIfPossible() which both touches native Core Audio
   // APIs and they can fail and disrupt tests during shutdown.
   in_shutdown_ = true;
   // We have seen cases where active input audio is not closed down properly
   // at browser shutdown. AudioInputController::Close() is called but tasks
   // in AudioInputController::DoClose() are not executed. Hence, input streams
   // might remain even at this late state.
   // TODO(henrika): figure out the real cause why streams are not closed
   // properly by the AIC for all cases and then remove this loop.
-  for (auto* stream : low_latency_input_streams_) {
+  auto low_latency_input_streams_copy = low_latency_input_streams_;

[tommi (sloooow) - chröme, 2016/07/08 12:06:59]

nit: add a comment above this line that explains why this is needed.  Something
like:

// |low_latency_input_streams_| will be modified during the call to
stream->Close(), so
// we can't iterate over it here.  Instead iterate over a copy.

[henrika (OOO until Aug 14), 2016/07/08 12:19:38]

Good idea, thanks!

+  for (auto* stream : low_latency_input_streams_copy) {
     LOG(WARNING) << "Closing existing audio input stream at destruction";
     // Prevents active Core Audio callbacks to use possibly invalid objects
     // in its OnData() callback.
     stream->Stop();
     // Avoids hitting CHECK in dtor of AudioManagerBase.
     stream->Close();
   }
   Shutdown();
 }
 
@@ skipping 690 matching lines @@
 ScopedAudioManagerPtr CreateAudioManager(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
     AudioLogFactory* audio_log_factory) {
   return ScopedAudioManagerPtr(
       new AudioManagerMac(std::move(task_runner), std::move(worker_task_runner),
                           audio_log_factory));
 }
 
 }  // namespace media