Merge AssociateStreamWithProducer message into CreateStream message for both audio output and input.

media/audio/audio_input_device.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.
 
 // Low-latency audio capturing class utilizing audio input stream provided
 // by a server (browser) process by use of an IPC interface.
 //
 // Relationship of classes:
 //
 //  AudioInputController                 AudioInputDevice
 //           ^                                  ^
 //           |                                  |
 //           v                  IPC             v
-// AudioInputRendererHost  <---------> AudioInputIPCDelegate
-//           ^                       (impl in AudioInputMessageFilter)
+// AudioInputRendererHost  <----------->  AudioInputIPC
+//           ^                            (AudioInputMessageFilter)
 //           |
 //           v
 // AudioInputDeviceManager
 //
 // Transportation of audio samples from the browser to the render process
 // is done by using shared memory in combination with a SyncSocket.
 // The AudioInputDevice user registers an AudioInputDevice::CaptureCallback by
 // calling Initialize().  The callback will be called with recorded audio from
 // the underlying audio layers.
 // The session ID is used by the AudioInputRendererHost to start the device
@@ skipping 29 matching lines @@
 //    Responsible for calling the CaptureCallback and feed audio samples from
 //    the server side audio layer using a socket and shared memory.
 //
 // Implementation notes:
 // - The user must call Stop() before deleting the class instance.
 
 #ifndef MEDIA_AUDIO_AUDIO_INPUT_DEVICE_H_
 #define MEDIA_AUDIO_AUDIO_INPUT_DEVICE_H_
 
 #include <string>
-#include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "media/audio/audio_device_thread.h"
 #include "media/audio/audio_input_ipc.h"
 #include "media/audio/audio_parameters.h"
 #include "media/audio/scoped_loop_observer.h"
 #include "media/base/audio_capturer_source.h"
 #include "media/base/media_export.h"
 
 namespace media {
 
 // TODO(henrika): This class is based on the AudioOutputDevice class and it has
 // many components in common. Investigate potential for re-factoring.
+// See http://crbug.com/179597.
 // TODO(henrika): Add support for event handling (e.g. OnStateChanged,
 // OnCaptureStopped etc.) and ensure that we can deliver these notifications
 // to any clients using this class.
 class MEDIA_EXPORT AudioInputDevice
     : NON_EXPORTED_BASE(public AudioCapturerSource),
       NON_EXPORTED_BASE(public AudioInputIPCDelegate),
       NON_EXPORTED_BASE(public ScopedLoopObserver) {
  public:
-  AudioInputDevice(AudioInputIPC* ipc,
+  // NOTE: Clients must call Initialize() before using.
+  AudioInputDevice(scoped_ptr<AudioInputIPC> ipc,
                    const scoped_refptr<base::MessageLoopProxy>& io_loop);
 
   // AudioCapturerSource implementation.
   virtual void Initialize(const AudioParameters& params,
                           CaptureCallback* callback,
                           CaptureEventHandler* event_handler) OVERRIDE;
   virtual void Start() OVERRIDE;
   virtual void Stop() OVERRIDE;
   virtual void SetVolume(double volume) OVERRIDE;
   virtual void SetDevice(int session_id) OVERRIDE;
   virtual void SetAutomaticGainControl(bool enabled) OVERRIDE;
 
  protected:
+  friend class base::RefCountedThreadSafe<AudioInputDevice>;
+  virtual ~AudioInputDevice();
+
   // Methods called on IO thread ----------------------------------------------
   // AudioInputIPCDelegate implementation.
   virtual void OnStreamCreated(base::SharedMemoryHandle handle,
                                base::SyncSocket::Handle socket_handle,
                                int length) OVERRIDE;
   virtual void OnVolume(double volume) OVERRIDE;
   virtual void OnStateChanged(
       AudioInputIPCDelegate::State state) OVERRIDE;
   virtual void OnDeviceReady(const std::string& device_id) OVERRIDE;
   virtual void OnIPCClosed() OVERRIDE;
 
-  friend class base::RefCountedThreadSafe<AudioInputDevice>;
-  virtual ~AudioInputDevice();
+ private:
+  // Note: The ordering of members in this enum is critical to correct behavior!

[palmer, 2013/03/05 21:09:32]

Maybe therefore assign them explicit values (IPC_CLOSED = 0, et c.).

[miu, 2013/03/06 22:36:52]

C++ spec requires enum values assigned as 0, 1, 2, ..., when not specified. 
However, I still agree with you about needing something safer than just a
comment to protect the validity of the code.  Therefore, I've added
COMPILE_ASSERTs in the constructor for both AudioOutputDevice and
AudioInputDevice.

+  enum State {
+    IPC_CLOSED,  // No more IPCs can take place.
+    IDLE,  // Not started.
+    STARTING_DEVICE,  // Waiting for OnDeviceReady() to be called back.
+    CREATING_STREAM,  // Waiting for OnStreamCreated() to be called back.
+    RECORDING,  // Receiving audio data.
+  };
 
- 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();
   void SetSessionIdOnIOThread(int session_id);
-  void StartOnIOThread();
+  void StartUpOnIOThread();
   void ShutDownOnIOThread();
   void SetVolumeOnIOThread(double volume);
   void SetAutomaticGainControlOnIOThread(bool enabled);
 
   // MessageLoop::DestructionObserver implementation for the IO loop.
   // If the IO loop dies before we do, we shut down the audio thread from here.
   virtual void WillDestroyCurrentMessageLoop() OVERRIDE;
 
   AudioParameters audio_parameters_;
 
   CaptureCallback* callback_;
   CaptureEventHandler* event_handler_;
 
-  AudioInputIPC* ipc_;
+  // A pointer to the IPC layer that takes care of sending requests over to
+  // the AudioInputRendererHost.  Only valid when state_ != IPC_CLOSED and must
+  // only be accessed on the IO thread.
+  scoped_ptr<AudioInputIPC> ipc_;
 
-  // Our stream ID on the message filter. Only modified on the IO thread.
-  int stream_id_;
+  // Current state (must only be accessed from the IO thread).  See comments for
+  // State enum above.
+  State state_;
 
   // The media session ID used to identify which input device to be started.
   // Only modified on the IO thread.
   int session_id_;
 
-  // State variable used to indicate it is waiting for a OnDeviceReady()
-  // callback. Only modified on the IO thread.
-  bool pending_device_ready_;
-
   // Stores the Automatic Gain Control state. Default is false.
   // Only modified on the IO thread.
   bool agc_is_enabled_;
 
   // Our audio thread callback class.  See source file for details.
   class AudioThreadCallback;
 
   // In order to avoid a race between OnStreamCreated and Stop(), we use this
   // guard to control stopping and starting the audio thread.
   base::Lock audio_thread_lock_;
   AudioDeviceThread audio_thread_;
   scoped_ptr<AudioInputDevice::AudioThreadCallback> audio_callback_;
 
+  // Temporary hack to ignore OnStreamCreated() due to the user calling Stop()
+  // so we don't start the audio thread pointing to a potentially freed
+  // |callback_|.
+  //
+  // TODO(miu): Replace this by changing AudioCapturerSource to accept the
+  // callback via Start(). See http://crbug.com/151051 for details.
+  bool stopping_hack_;
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioInputDevice);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_INPUT_DEVICE_H_