Add support for audio input mute detection on all platforms

media/audio/pulse/pulse_input.h

Index: media/audio/pulse/pulse_input.h
diff --git a/media/audio/pulse/pulse_input.h b/media/audio/pulse/pulse_input.h
index 60acf2f908719891974eee38326fe528b64d615d..dd42b31489ef0f1cc4e25082eb75ecc556e336a4 100644
--- a/media/audio/pulse/pulse_input.h
+++ b/media/audio/pulse/pulse_input.h
@@ -5,6 +5,7 @@
 #ifndef MEDIA_AUDIO_PULSE_PULSE_INPUT_H_
 #define MEDIA_AUDIO_PULSE_PULSE_INPUT_H_
 
+#include <pulse/pulseaudio.h>
 #include <string>
 
 #include "base/threading/thread_checker.h"
@@ -14,11 +15,6 @@
 #include "media/audio/audio_parameters.h"
 #include "media/base/audio_block_fifo.h"
 
-struct pa_context;
-struct pa_source_info;
-struct pa_stream;
-struct pa_threaded_mainloop;
-
 namespace media {
 
 class AudioManagerPulse;
@@ -41,6 +37,7 @@ class PulseAudioInputStream : public AgcAudioStream<AudioInputStream> {
   virtual double GetMaxVolume() override;
   virtual void SetVolume(double volume) override;
   virtual double GetVolume() override;
+  virtual bool IsMuted() override;
 
  private:
   // PulseAudio Callbacks.
@@ -48,10 +45,17 @@ class PulseAudioInputStream : public AgcAudioStream<AudioInputStream> {
   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();
 
+  // Utility method used by GetVolume() and IsMuted().
+  bool GetSourceInformation(pa_source_info_cb_t callback);
+
   AudioManagerPulse* audio_manager_;
   AudioInputCallback* callback_;
   std::string device_name_;
@@ -60,6 +64,10 @@ class PulseAudioInputStream : public AgcAudioStream<AudioInputStream> {
   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_;