content/browser/media/audio_state_provider.h

   1 // Copyright 2015 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_BROWSER_MEDIA_AUDIO_STATE_PROVIDER_H_
   6 #define CONTENT_BROWSER_MEDIA_AUDIO_STATE_PROVIDER_H_
   7
   8 #include "content/common/content_export.h"
   9
  10 namespace content {
  11 class WebContents;
  12 class AudioStreamMonitor;
  13
  14 // This class is associated with a WebContents, and maintains the audible
  15 // state regarding all the players in it.
  16 // The audible state is true if at least one player is playing a sound.
  17 // Whenever the audible state of the WebContents as a whole changes, this
  18 // class sends a notification to it.
  19 //
  20 // Each WebContentsImpl owns an AudioStateProvider
  21 class CONTENT_EXPORT AudioStateProvider {
  22  public:
  23   explicit AudioStateProvider(WebContents* web_contents);
  24   virtual ~AudioStateProvider() {}
  25
  26   // Indicates whether this service is available on the system.
  27   virtual bool IsAudioStateAvailable() const = 0;
  28
  29   // If this provider uses monitoring (i.e. measure the signal),
  30   // return its monitor.
  31   virtual AudioStreamMonitor* audio_stream_monitor() = 0;
  32
  33   // Returns true if the WebContents is playing or has recently been
  34   // playing the sound.
  35   virtual bool WasRecentlyAudible() const;
  36
  37   void set_was_recently_audible_for_testing(bool value) {
  38     was_recently_audible_ = value;
  39   }
  40
  41  protected:
  42   // Notify WebContents that the audio state has changed.
  43   void Notify(bool new_state);
  44
  45   // The WebContents instance instance to receive indicator toggle
  46   // notifications.  This pointer should be valid for the lifetime of
  47   // AudioStreamMonitor.
  48   WebContents* const web_contents_;
  49
  50   // The audio state that is being maintained
  51   bool  was_recently_audible_;
  52
  53 };
  54
  55 }  // namespace content
  56
  57 #endif  // CONTENT_BROWSER_MEDIA_AUDIO_STATE_PROVIDER_H_