Move some generic functions to AudioManagerBase to be inherited by platform-specific AudioManager***

media/audio/audio_manager_base.h

 // 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.
 
 #ifndef MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 #define MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
 
 #include <map>
 
 #include "base/atomic_ref_count.h"
@@ skipping 20 matching lines @@
 
   virtual void Init() OVERRIDE;
 
   virtual scoped_refptr<base::MessageLoopProxy> GetMessageLoop() OVERRIDE;
 
   virtual string16 GetAudioInputDeviceModel() OVERRIDE;
 
   virtual bool CanShowAudioInputSettings() OVERRIDE;
   virtual void ShowAudioInputSettings() OVERRIDE;
 
-  virtual void GetAudioInputDeviceNames(media::AudioDeviceNames* device_names)
-      OVERRIDE;
+  virtual void GetAudioInputDeviceNames(
+      media::AudioDeviceNames* device_names) OVERRIDE;
+
+  virtual AudioOutputStream* MakeAudioOutputStream(
+      const AudioParameters& params) OVERRIDE;
+
+  virtual AudioInputStream* MakeAudioInputStream(
+      const AudioParameters& params, const std::string& device_id) OVERRIDE;
 
   virtual AudioOutputStream* MakeAudioOutputStreamProxy(
       const AudioParameters& params) OVERRIDE;
 
   virtual bool IsRecordingInProcess() OVERRIDE;
 
+  // Called internally by the audio stream when it has been closed.
+  virtual void ReleaseOutputStream(AudioOutputStream* stream);
+  virtual void ReleaseInputStream(AudioInputStream* stream);
+
   void IncreaseActiveInputStreamCount();
   void DecreaseActiveInputStreamCount();
 
   // Shuts down the audio thread and releases all the audio output dispatchers
   // on the audio thread.  All AudioOutputProxy instances should be freed before
   // Shutdown is called.
   void Shutdown();
 
+  // Returns the platform specific number of audio streams allowed. This is a
+  // practical limit to prevent failure caused by too many audio streams opened.
+  virtual int GetMaxOutputStreamsAllowed() = 0;

[tommi (sloooow) - chröme, 2012/03/06 16:16:04]

nit: Instead of a pure virtual function + implementation everywhere, we could
just have an int member variable in this class and an inline setter that can be
called in the constructor of the derived classes.

 protected:
  void set_max_output_streams(int max) { max_output_streams_ = max; }

 private:
  int max_output_streams_;  // initialized to something reasonable.


Then in derived classes:

MySpecialAudioManager() {
  set_max_output_streams(10);
}

[no longer working on chromium, 2012/03/06 17:38:41]

Done.

+
+  // Creates the output stream for the |AUDIO_PCM_LINEAR format|. The legacy
+  // name is also from |AUDIO_PCM_LINEAR|.
+  virtual AudioOutputStream* MakeLinearOutputStream(
+      const AudioParameters& params) = 0;
+
+  // Creates the output stream for the |AUDIO_PCM_LOW_LATENCY| format.
+  virtual AudioOutputStream* MakeLowLatencyOutputStream(
+      const AudioParameters& params) = 0;
+
+  // Creates the input stream for the |AUDIO_PCM_LINEAR format|. The legacy
+  // name is also from |AUDIO_PCM_LINEAR|.
+  virtual AudioInputStream* MakeLinearInputStream(
+      const AudioParameters& params, const std::string& device_id) = 0;
+
+  // Creates the input stream for the |AUDIO_PCM_LOW_LATENCY| format.
+  virtual AudioInputStream* MakeLowLatencyInputStream(
+      const AudioParameters& params, const std::string& device_id) = 0;
+
  protected:
   AudioManagerBase();
 
   typedef std::map<AudioParameters, scoped_refptr<AudioOutputDispatcher>,
                    AudioParameters::Compare>
       AudioOutputDispatchersMap;
 
   void ShutdownOnAudioThread();
 
   // Thread used to interact with AudioOutputStreams created by this
   // audio manger.
   scoped_ptr<base::Thread> audio_thread_;
   mutable base::Lock audio_thread_lock_;
 
   // Map of cached AudioOutputDispatcher instances.  Must only be touched
   // from the audio thread (no locking).
   AudioOutputDispatchersMap output_dispatchers_;
 
   // Counts the number of active input streams to find out if something else
   // is currently recording in Chrome.
   base::AtomicRefCount num_active_input_streams_;
 
+  // Number of currently open output streams.
+  int num_output_streams_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioManagerBase);
 };
 
 #endif  // MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_