Add MediaStream.active attribute

Source/platform/mediastream/MediaStreamDescriptor.h

Index: Source/platform/mediastream/MediaStreamDescriptor.h
diff --git a/Source/platform/mediastream/MediaStreamDescriptor.h b/Source/platform/mediastream/MediaStreamDescriptor.h
index 30d5c6ddc6ca00127994d602af66499a522839b7..5aedb14261af45d69151cc92bc721004c2bb5110 100644
--- a/Source/platform/mediastream/MediaStreamDescriptor.h
+++ b/Source/platform/mediastream/MediaStreamDescriptor.h
@@ -80,6 +80,9 @@ public:
     void addRemoteTrack(MediaStreamComponent*);
     void removeRemoteTrack(MediaStreamComponent*);
 
+    bool active() const { return m_active; }
+    void setActive(bool active) { m_active = active; }
+
     bool ended() const { return m_ended; }
     void setEnded() { m_ended = true; }
 
@@ -94,6 +97,7 @@ private:
     String m_id;
     Vector<RefPtr<MediaStreamComponent>> m_audioComponents;
     Vector<RefPtr<MediaStreamComponent>> m_videoComponents;
+    bool m_active;
     bool m_ended;
 
     OwnPtr<ExtraData> m_extraData;