Add support for audio input mute detection on all platforms

media/audio/pulse/pulse_input.cc

Index: media/audio/pulse/pulse_input.cc
diff --git a/media/audio/pulse/pulse_input.cc b/media/audio/pulse/pulse_input.cc
index 14ef242759a68d48db6da943ebb899b1089c3cf6..3043f6a96902c748f62b5ef4fcc37ef5863294cb 100644
--- a/media/audio/pulse/pulse_input.cc
+++ b/media/audio/pulse/pulse_input.cc
@@ -4,8 +4,6 @@
 
 #include "media/audio/pulse/pulse_input.h"
 
-#include <pulse/pulseaudio.h>
-
 #include "base/logging.h"
 #include "media/audio/pulse/audio_manager_pulse.h"
 #include "media/audio/pulse/pulse_util.h"
@@ -30,6 +28,7 @@ PulseAudioInputStream::PulseAudioInputStream(AudioManagerPulse* audio_manager,
       channels_(0),
       volume_(0.0),
       stream_started_(false),
+      muted_(false),
       fifo_(params.channels(),
             params.frames_per_buffer(),
             kNumberOfBlocksBufferInFifo),
@@ -185,20 +184,17 @@ double PulseAudioInputStream::GetVolume() {
     // Return zero and the callback will asynchronously update the |volume_|.
     return 0.0;
   } else {
-    // Called by other thread, put an AutoPulseLock and wait for the operation.
-    AutoPulseLock auto_lock(pa_mainloop_);
-    if (!handle_)
-      return 0.0;
-
-    size_t index = pa_stream_get_device_index(handle_);
-    pa_operation* operation = pa_context_get_source_info_by_index(
-        pa_context_, index, &VolumeCallback, this);
-    WaitForOperationCompletion(pa_mainloop_, operation);
-
+    GetSourceInformation(&VolumeCallback);
     return volume_;
   }
 }
 
+bool PulseAudioInputStream::IsMuted() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  GetSourceInformation(&MuteCallback);
+  return muted_;
+}
+
 // static, used by pa_stream_set_read_callback.
 void PulseAudioInputStream::ReadCallback(pa_stream* handle,
                                          size_t length,
@@ -236,6 +232,22 @@ void PulseAudioInputStream::VolumeCallback(pa_context* context,
   stream->volume_ = static_cast<double>(volume);
 }
 
+// static, used by pa_context_get_source_info_by_index.
+void PulseAudioInputStream::MuteCallback(pa_context* context,

[tommi (sloooow) - chröme, 2014/10/15 17:00:48]

on which thread does this callback run?  Is it safe to touch muted_ here?
If we can add a thread check, that would be good.

[henrika (OOO until Aug 14), 2014/10/16 09:58:00]

Done.

[henrika (OOO until Aug 14), 2014/10/16 09:58:00]

Based on off-line discussion. Will add comment.

+                                         const pa_source_info* info,
+                                         int error,
+                                         void* user_data) {
+  PulseAudioInputStream* stream =
+      reinterpret_cast<PulseAudioInputStream*>(user_data);
+
+  if (error) {
+    pa_threaded_mainloop_signal(stream->pa_mainloop_, 0);

[tommi (sloooow) - chröme, 2014/10/15 17:00:48]

Can you document why we need to call this here and why we only call it if
there's an error?

I'm a bit confused why StreamNotifyCallback always calls it and VolumeCallback
doesn't.

[henrika (OOO until Aug 14), 2014/10/16 09:58:00]

Discussed off-line.

+    return;
+  }
+
+  stream->muted_ = static_cast<bool>(info->mute);

[tommi (sloooow) - chröme, 2014/10/15 17:00:48]

stream->muted_ = info->mute != 0;

[henrika (OOO until Aug 14), 2014/10/16 09:58:00]

Done.

+}
+
 // static, used by pa_stream_set_state_callback.
 void PulseAudioInputStream::StreamNotifyCallback(pa_stream* s,
                                                  void* user_data) {
@@ -301,4 +313,16 @@ void PulseAudioInputStream::ReadData() {
   pa_threaded_mainloop_signal(pa_mainloop_, 0);
 }
 
+bool PulseAudioInputStream::GetSourceInformation(pa_source_info_cb_t callback) {
+  AutoPulseLock auto_lock(pa_mainloop_);
+  if (!handle_)
+    return false;
+
+  size_t index = pa_stream_get_device_index(handle_);
+  pa_operation* operation =
+      pa_context_get_source_info_by_index(pa_context_, index, callback, this);
+  WaitForOperationCompletion(pa_mainloop_, operation);
+  return true;
+}
+
 }  // namespace media