Refactor AudioInputDevice to remove race conditions and allow more flexible calling sequences.

content/renderer/media/audio_input_device.h

 // Copyright (c) 2011 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.
 
 // Low-latency audio capturing unit utilizing audio input stream provided
 // by browser process through IPC.
 //
 // Relationship of classes.
 //
 //  AudioInputController                 AudioInputDevice
@@ skipping 62 matching lines @@
     virtual ~CaptureCallback() {}
   };
 
   // Methods called on main render thread -------------------------------------
   AudioInputDevice(size_t buffer_size,
                    int channels,
                    double sample_rate,
                    CaptureCallback* callback);
   virtual ~AudioInputDevice();
 
-  // Starts audio capturing. Returns |true| on success.
-  bool Start();
+  // Starts audio capturing.
+  void Start();
 
   // Stops audio capturing. Returns |true| on success.
   bool Stop();
 
   // Sets the capture volume scaling, with range [0.0, 1.0] inclusive.
   // Returns |true| on success.
   bool SetVolume(double volume);
 
   // Gets the capture volume scaling, with range [0.0, 1.0] inclusive.
   // Returns |true| on success.
   bool GetVolume(double* volume);
 
   double sample_rate() const { return sample_rate_; }
   size_t buffer_size() const { return buffer_size_; }
 
   // Methods called on IO thread ----------------------------------------------
   // AudioInputMessageFilter::Delegate impl., called by AudioInputMessageFilter
   virtual void OnLowLatencyCreated(base::SharedMemoryHandle handle,
                                    base::SyncSocket::Handle socket_handle,
                                    uint32 length);
   virtual void OnVolume(double volume);
 
  private:
   // Methods called on IO thread ----------------------------------------------
   // The following methods are tasks posted on the IO thread that needs to
   // be executed on that thread. They interact with AudioInputMessageFilter and
   // sends IPC messages on that thread.
   void InitializeOnIOThread(const AudioParameters& params);
   void StartOnIOThread();
-  void ShutDownOnIOThread();
+  void ShutDownOnIOThread(base::WaitableEvent* completion);
   void SetVolumeOnIOThread(double volume);
 
   void Send(IPC::Message* message);
 
   // Method called on the audio thread ----------------------------------------
   // Calls the client's callback for capturing audio.
   void FireCaptureCallback();
 
   // DelegateSimpleThread::Delegate implementation.
   virtual void Run();
@@ skipping 31 matching lines @@
   // Our stream ID on the message filter. Only modified on the IO thread.
   int32 stream_id_;
 
   scoped_ptr<base::SharedMemory> shared_memory_;
   scoped_ptr<base::SyncSocket> socket_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioInputDevice);
 };
 
 #endif  // CONTENT_RENDERER_MEDIA_AUDIO_INPUT_DEVICE_H_