Getting rid of AudioHardwareConfig and its synchronous IPC.

content/renderer/media/audio_renderer_sink_cache_impl.h

 // Copyright 2016 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.
 
 #ifndef CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_SINK_CACHE_IMPL_H_
 #define CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_SINK_CACHE_IMPL_H_
 
 #include "content/renderer/media/audio_renderer_sink_cache.h"
 
 #include <vector>
 
+#include "base/optional.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/time/time.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 // AudioRendererSinkCache implementation.
 class CONTENT_EXPORT AudioRendererSinkCacheImpl
     : public AudioRendererSinkCache {
@@ skipping 62 matching lines @@
   // the same sink is requested in GetSink(), if time interval between (1) and
   // (2) is less than |kDeleteTimeoutMs|, then sink cached in (1) is reused in
   // (2). On the other hand, if after (1) nobody is interested in the sink
   // within |kDeleteTimeoutMs|, it is garbage-collected.
   const base::TimeDelta delete_timeout_;
 
   // Cached sinks, protected by lock.
   base::Lock cache_lock_;
   CacheContainer cache_;
 
+  // Cached default output device information. Since access to the default
+  // device is always allowed, this information can be cashed and shared among

[DaleCurtis, 2016/07/06 18:53:37]

cached.

[o1ka, 2016/07/13 09:52:41]

n/a any more

+  // all the clients. It is updated on the first request if not initialized yet,
+  // and each time a new default device sink is created in the cache.
+  base::Optional<media::OutputDeviceInfo> default_device_info_;
+
   // Weak pointer to be used for delayed sink deletion on |task_runner_|.
   // Pre-created in constructor and is used to post all the delayed tasks.
   // A delayed task can be concurrently posted from any thread the cache is used
   // on, so on-the-flight weak pointer creation with
   // weak_ptr_factory_.GetWeakPtr() can't be used, because it will result in the
   // racy access to the factory.
   base::WeakPtr<AudioRendererSinkCacheImpl> weak_this_;
 
   // Used to produce |weak_this_| on AudioRendererSinkCacheImpl construction.
   base::WeakPtrFactory<AudioRendererSinkCacheImpl> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioRendererSinkCacheImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_RENDERER_SINK_CACHE_IMPL_H_