Propagate muted state from MediaStreamAudioSource into JS.

content/renderer/media/media_stream_source.cc

Index: content/renderer/media/media_stream_source.cc
diff --git a/content/renderer/media/media_stream_source.cc b/content/renderer/media/media_stream_source.cc
index 3334bfd57120d66fa4bbd13cac1a12a50d968479..890cc69a66e484683cdf33424193d43f13a7fdc8 100644
--- a/content/renderer/media/media_stream_source.cc
+++ b/content/renderer/media/media_stream_source.cc
@@ -26,6 +26,16 @@ void MediaStreamSource::StopSource() {
   Owner().SetReadyState(blink::WebMediaStreamSource::kReadyStateEnded);
 }
 
+void MediaStreamSource::SetSourceMuted(bool is_muted) {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  // Although this change is valid only if the ready state isn't already Ended,
+  // there's code further along (like in blink::MediaStreamTrack) which filters
+  // that out alredy.
+  Owner().SetReadyState(is_muted
+                            ? blink::WebMediaStreamSource::kReadyStateMuted
+                            : blink::WebMediaStreamSource::kReadyStateLive);
+}
+
 void MediaStreamSource::SetDeviceInfo(const StreamDeviceInfo& device_info) {
   DCHECK(thread_checker_.CalledOnValidThread());
   device_info_ = device_info;