Add AudioStreamRegistry. Move stream counting logic

media/audio/audio_streams_tracker.cc

 // Copyright 2015 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/audio_streams_tracker.h"
 
 #include <limits>
 
 namespace media {
 
@@ skipping 23 matching lines @@
 void AudioStreamsTracker::ResetMaxStreamCount() {
   DCHECK(thread_checker_.CalledOnValidThread());
   max_stream_count_ = current_stream_count_;
 }
 
 size_t AudioStreamsTracker::max_stream_count() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return max_stream_count_;
 }
 
+void AudioStreamsTracker::DetachFromThreadForTesting() {
+  DCHECK_EQ(current_stream_count_, 0u);
+  DCHECK(thread_checker_.CalledOnValidThread());
+  thread_checker_.DetachFromThread();
+}
+
 }  // namespace media