media_observer.h revision 116680a4aac90f2aa7413d9095a592090648e557 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CONTENT_PUBLIC_BROWSER_MEDIA_OBSERVER_H_
6#define CONTENT_PUBLIC_BROWSER_MEDIA_OBSERVER_H_
7
8#include "base/callback_forward.h"
9#include "content/public/browser/media_request_state.h"
10#include "content/public/common/media_stream_request.h"
11
12namespace content {
13
14// An embedder may implement MediaObserver and return it from
15// ContentBrowserClient to receive callbacks as media events occur.
16class MediaObserver {
17 public:
18  // Called when a audio capture device is plugged in or unplugged.
19  virtual void OnAudioCaptureDevicesChanged() = 0;
20
21  // Called when a video capture device is plugged in or unplugged.
22  virtual void OnVideoCaptureDevicesChanged() = 0;
23
24  // Called when a media request changes state.
25  virtual void OnMediaRequestStateChanged(
26      int render_process_id,
27      int render_frame_id,
28      int page_request_id,
29      const GURL& security_origin,
30      MediaStreamType stream_type,
31      MediaRequestState state) = 0;
32
33  // Called when an audio stream is being created.
34  virtual void OnCreatingAudioStream(int render_process_id,
35                                     int render_frame_id) = 0;
36
37  // Called when an audio stream transitions into a playing state.
38  // |power_read_callback| is a thread-safe callback, provided for polling the
39  // current audio signal power level, and any copies/references to it must be
40  // destroyed when OnAudioStreamStopped() is called.
41  //
42  // The callback returns the current power level (in dBFS units) and the clip
43  // status (true if any part of the audio signal has clipped since the last
44  // callback run).  See media/audio/audio_power_monitor.h for more info.
45  typedef base::Callback<std::pair<float, bool>()> ReadPowerAndClipCallback;
46  virtual void OnAudioStreamPlaying(
47      int render_process_id,
48      int render_frame_id,
49      int stream_id,
50      const ReadPowerAndClipCallback& power_read_callback) = 0;
51
52  // Called when an audio stream has stopped.
53  virtual void OnAudioStreamStopped(
54      int render_process_id,
55      int render_frame_id,
56      int stream_id) = 0;
57
58 protected:
59  virtual ~MediaObserver() {}
60};
61
62}  // namespace content
63
64#endif  // CONTENT_PUBLIC_BROWSER_MEDIA_OBSERVER_H_
65