content/public/browser/media_observer.h

   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
  12 namespace content {
  13
  14 // An embedder may implement MediaObserver and return it from
  15 // ContentBrowserClient to receive callbacks as media events occur.
  16 class 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_view_id,
  28       int page_request_id,
  29       const GURL& security_origin,
  30       const MediaStreamDevice& device,
  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_