Refactor MediaStreamManager to never output real device id. It now always output sourceId in the fo…

content/renderer/media/mock_media_stream_dispatcher.cc

Index: content/renderer/media/mock_media_stream_dispatcher.cc
diff --git a/content/renderer/media/mock_media_stream_dispatcher.cc b/content/renderer/media/mock_media_stream_dispatcher.cc
index a1b9527959fe6c7baac2de3d64ea126eae0f8fb6..823af11ca1db50195c3a77ea08db04e5fae354b7 100644
--- a/content/renderer/media/mock_media_stream_dispatcher.cc
+++ b/content/renderer/media/mock_media_stream_dispatcher.cc
@@ -34,7 +34,7 @@ void MockMediaStreamDispatcher::GenerateStream(
 
   if (IsAudioMediaType(components.audio_type)) {
     StreamDeviceInfo audio;
-    audio.device.id = "audio_device_id";
+    audio.device.id = base::StringPrintf("%s%d","audio_device_id", session_id_);
     audio.device.name = "microphone";
     audio.device.type = components.audio_type;
     audio.session_id = session_id_;
@@ -42,7 +42,7 @@ void MockMediaStreamDispatcher::GenerateStream(
   }
   if (IsVideoMediaType(components.video_type)) {
     StreamDeviceInfo video;
-    video.device.id = "video_device_id";
+    video.device.id = base::StringPrintf("%s%d","video_device_id", session_id_);
     video.device.name = "usb video camera";
     video.device.type = components.video_type;
     video.session_id = session_id_;