Caching AudioOutputDevice instances in mixer manager

media/base/audio_renderer_mixer_pool.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 MEDIA_BASE_AUDIO_RENDERER_MIXER_POOL_H_
+#define MEDIA_BASE_AUDIO_RENDERER_MIXER_POOL_H_
+
+#include <string>
+
+#include "media/base/output_device_info.h"
+
+namespace url {
+class Origin;
+}
+
+namespace media {
+class AudioParameters;
+class AudioRendererMixer;
+
+class AudioRendererMixerPool {
+ public:
+  AudioRendererMixerPool() {}
+  virtual ~AudioRendererMixerPool() {}
+
+  // Obtains a pointer to mixer instance based on AudioParameters. The pointer
+  // is guaranteed to be valid (at least) until it's rereleased by a call to
+  // ReturnMixer()
+  virtual media::AudioRendererMixer* GetMixer(
+      int source_render_frame_id,
+      const media::AudioParameters& params,
+      const std::string& device_id,
+      const url::Origin& security_origin,
+      media::OutputDeviceStatus* device_status) = 0;
+
+  // Returns mixer back to the pool.
+  virtual void ReturnMixer(int source_render_frame_id,
+                           const media::AudioParameters& params,
+                           const std::string& device_id,
+                           const url::Origin& security_origin) = 0;
+
+  // Returns output device information
+  virtual media::OutputDeviceInfo GetOutputDeviceInfo(
+      int source_render_frame_id,
+      int session_id,
+      const std::string& device_id,
+      const url::Origin& security_origin) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AudioRendererMixerPool);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_AUDIO_RENDERER_MIXER_POOL_H_