Add support for audio input mute detection on all platforms

media/audio/mac/audio_low_latency_input_mac.cc

Index: media/audio/mac/audio_low_latency_input_mac.cc
diff --git a/media/audio/mac/audio_low_latency_input_mac.cc b/media/audio/mac/audio_low_latency_input_mac.cc
index 1baa09f1fe07f0e2b4d5a89c017eaf53c8a23247..2b2ce0090da0f54d25fdb9a40f60eb5e7f417b14 100644
--- a/media/audio/mac/audio_low_latency_input_mac.cc
+++ b/media/audio/mac/audio_low_latency_input_mac.cc
@@ -451,6 +451,29 @@ double AUAudioInputStream::GetVolume() {
   return 0.0;
 }
 
+bool AUAudioInputStream::IsMuted() {
+  // Verify that we have a valid device.
+  DCHECK_NE(input_device_id_, kAudioObjectUnknown) << "Device ID is unknown";
+
+  AudioObjectPropertyAddress property_address = {
+    kAudioDevicePropertyMute,
+    kAudioDevicePropertyScopeInput,
+    kAudioObjectPropertyElementMaster
+  };
+
+  if (!AudioObjectHasProperty(input_device_id_, &property_address)) {
+    DLOG(ERROR) << "Device does not support checking master mute state";
+    return false;
+  }
+
+  UInt32 muted = 0;
+  UInt32 size = sizeof(muted);
+  OSStatus result = AudioObjectGetPropertyData(
+      input_device_id_, &property_address, 0, NULL, &size, &muted);
+  DLOG_IF(WARNING, result != noErr) << "Failed to get mute state";
+  return result == noErr && muted != 0;
+}
+
 // AUHAL AudioDeviceOutput unit callback
 OSStatus AUAudioInputStream::InputProc(void* user_data,
                                        AudioUnitRenderActionFlags* flags,