Avoid shutdown crash if audio thread is hung.

media/audio/audio_manager_base.cc

Index: media/audio/audio_manager_base.cc
diff --git a/media/audio/audio_manager_base.cc b/media/audio/audio_manager_base.cc
index 92a255d095cfb22ed58b36b766c22aa8084b2d58..72f9a336d73683251c5dedd9800b65d2c0b35d9c 100644
--- a/media/audio/audio_manager_base.cc
+++ b/media/audio/audio_manager_base.cc
@@ -98,9 +98,9 @@ AudioManagerBase::AudioManagerBase(std::unique_ptr<AudioThread> audio_thread,
 
 AudioManagerBase::~AudioManagerBase() {
   // All the output streams should have been deleted.
-  CHECK_EQ(0, num_output_streams_);
+  DCHECK_EQ(0, num_output_streams_);

[alokp, 2017/06/13 23:35:51]

Changing CHECKs in the constructor to DCHECKs since we are intentionally leaking
these streams if audio thread is hung.

[DaleCurtis, 2017/06/13 23:43:15]

I think a better option would be to skip AM::Shutdown(), ~AM and ~AudioSystem if
the audio thread is hung and mark it as a "TODO(olka, grunell): Will be fixed
when audio is its own process."

[alokp, 2017/06/14 17:34:35]

Good idea. Done.

   // All the input streams should have been deleted.
-  CHECK(input_streams_.empty());
+  DCHECK(input_streams_.empty());
 }
 
 base::string16 AudioManagerBase::GetAudioInputDeviceModel() {