Add support for audio input mute detection on all platforms

media/audio/pulse/pulse_input.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_PULSE_PULSE_INPUT_H_
 #define MEDIA_AUDIO_PULSE_PULSE_INPUT_H_
 
 #include <string>
 
 #include "base/threading/thread_checker.h"
@@ skipping 23 matching lines @@
   virtual ~PulseAudioInputStream();
 
   // Implementation of AudioInputStream.
   virtual bool Open() override;
   virtual void Start(AudioInputCallback* callback) override;
   virtual void Stop() override;
   virtual void Close() override;
   virtual double GetMaxVolume() override;
   virtual void SetVolume(double volume) override;
   virtual double GetVolume() override;
+  virtual bool IsMuted() override;
 
  private:
   // PulseAudio Callbacks.
   static void ReadCallback(pa_stream* handle, size_t length, void* user_data);
   static void StreamNotifyCallback(pa_stream* stream, void* user_data);
   static void VolumeCallback(pa_context* context, const pa_source_info* info,
                              int error, void* user_data);
+  static void MuteCallback(pa_context* context, const pa_source_info* info,
+                             int error, void* user_data);
 
   // Helper for the ReadCallback.
   void ReadData();
 
   AudioManagerPulse* audio_manager_;
   AudioInputCallback* callback_;
   std::string device_name_;
   AudioParameters params_;
   int channels_;
   double volume_;
   bool stream_started_;
 
+  // Set to true in IsMuted() if user has muted the selected microphone in the
+  // sound settings UI.
+  bool muted_;
+
   // Holds the data from the OS.
   AudioBlockFifo fifo_;
 
   // PulseAudio API structs.
   pa_threaded_mainloop* pa_mainloop_; // Weak.
   pa_context* pa_context_;  // Weak.
   pa_stream* handle_;
 
   // Flag indicating the state of the context has been changed.
   bool context_state_changed_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(PulseAudioInputStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_PULSE_PULSE_INPUT_H_