First step towards moving AudioDevice from content/ to media/audio.

media/audio/audio_input_ipc.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_INPUT_IPC_H_
+#define MEDIA_AUDIO_AUDIO_INPUT_IPC_H_
+
+#include "base/shared_memory.h"
+#include "base/sync_socket.h"
+#include "media/audio/audio_parameters.h"
+#include "media/base/media_export.h"
+
+namespace media {
+
+// Contains IPC notifications for the state of the server side
+// (AudioInputController) audio state changes and when an AudioInputController
+// has been created.  Implemented by AudioInputDevice.
+class MEDIA_EXPORT AudioInputIPCDelegate {
+ public:
+  // Valid states for the input stream.
+  enum State {
+    kRecording,
+    kStopped,
+    kError
+  };
+
+  // Called when an AudioInputController has been created.
+  // The shared memory |handle| points to a memory section that's used to
+  // transfer data between the AudioInputDevice and AudioInputController
+  // objects.  The implementation of OnStreamCreated takes ownership.
+  // The |socket_handle| is used by the AudioInputController to signal
+  // notifications that more data is available and can optionally provide
+  // parameter changes back.  The AudioInputDevice must read from this socket
+  // and process the shared memory whenever data is read from the socket.
+  virtual void OnStreamCreated(base::SharedMemoryHandle handle,
+                               base::SyncSocket::Handle socket_handle,
+                               int length) = 0;
+
+  // Called when state of an audio stream has changed.
+  virtual void OnStateChanged(State state) = 0;
+
+  // Called when the input stream volume has changed.
+  virtual void OnVolume(double volume) = 0;
+
+  // Called when a device has been started on the server side.
+  // If the device could not be started, |device_id| will be empty.
+  virtual void OnDeviceReady(const std::string& device_id) = 0;
+
+  // Called when the AudioInputIPC object is going away and/or when the
+  // IPC channel has been closed and no more IPC requests can be made.
+  // Implementations must clear any references to the AudioInputIPC object
+  // at this point.
+  virtual void OnIPCClosed() = 0;
+
+ protected:
+  virtual ~AudioInputIPCDelegate();
+};
+
+// Provides IPC functionality for an AudioInputDevice.  The implementation
+// should asynchronously deliver the messages to an AudioInputController object
+// (or create one in the case of CreateStream()), that may live in a separate
+// process.
+class MEDIA_EXPORT AudioInputIPC {
+ public:
+  // Registers an AudioInputIPCDelegate and returns a |stream_id| that
+  // must be used with all other IPC functions in this interface.
+  virtual int AddDelegate(AudioInputIPCDelegate* delegate) = 0;
+
+  // Unregisters a delegate that was previously registered via a call to
+  // AddDelegate().  The audio stream should be in a closed state prior to
+  // calling this function.
+  virtual void RemoveDelegate(int stream_id) = 0;
+
+  // Sends a request to create an AudioInputController object in the peer
+  // process, identify it by |stream_id| and configure it to use the specified
+  // audio |params|.  Once the stream has been created, the implementation must
+  // generate a notification to the AudioInputIPCDelegate and call
+  // OnStreamCreated().
+  virtual void CreateStream(int stream_id, const AudioParameters& params,
+      const std::string& device_id, bool automatic_gain_control) = 0;
+
+  // Starts the device on the server side.  Once the device has started,
+  // or failed to start, a callback to
+  // AudioInputIPCDelegate::OnDeviceReady() must be made.
+  virtual void StartDevice(int stream_id, int session_id) = 0;
+
+  // Corresponds to a call to AudioInputController::Record() on the server side.
+  virtual void RecordStream(int stream_id) = 0;
+
+  // Sets the volume of the audio stream.
+  virtual void SetVolume(int stream_id, double volume) = 0;
+
+  // Closes the audio stream and deletes the matching AudioInputController
+  // instance.  Prior to deleting the AudioInputController object, a call to
+  // AudioInputController::Close must be made.
+  virtual void CloseStream(int stream_id) = 0;
+
+ protected:
+  virtual ~AudioInputIPC();
+};
+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_AUDIO_INPUT_IPC_H_