--- a/dom/media/MediaRecorder.cpp
+++ b/dom/media/MediaRecorder.cpp
@@ -380,17 +380,35 @@ public:
     mLastBlobTimeStamp = TimeStamp::Now();
   }
 
   void Start()
   {
     LOG(LogLevel::Debug, ("Session.Start %p", this));
     MOZ_ASSERT(NS_IsMainThread());
 
-    SetupStreams();
+    // Create a Track Union Stream
+    MediaStreamGraph* gm = mRecorder->GetSourceMediaStream()->Graph();
+    mTrackUnionStream = gm->CreateTrackUnionStream(nullptr);
+    MOZ_ASSERT(mTrackUnionStream, "CreateTrackUnionStream failed");
+
+    mTrackUnionStream->SetAutofinish(true);
+
+    // Bind this Track Union Stream with Source Media.
+    mInputPort = mTrackUnionStream->AllocateInputPort(mRecorder->GetSourceMediaStream());
+
+    DOMMediaStream* domStream = mRecorder->Stream();
+    if (domStream) {
+      // Get the track type hint from DOM media stream.
+      TracksAvailableCallback* tracksAvailableCallback = new TracksAvailableCallback(this);
+      domStream->OnTracksAvailable(tracksAvailableCallback);
+    } else {
+      // Web Audio node has only audio.
+      InitEncoder(ContainerWriter::CREATE_AUDIO_TRACK);
+    }
   }
 
   void Stop()
   {
     LOG(LogLevel::Debug, ("Session.Stop %p", this));
     MOZ_ASSERT(NS_IsMainThread());
     mStopIssued = true;
     CleanupStreams();
@@ -522,42 +540,16 @@ private:
       if (NS_FAILED(NS_DispatchToMainThread(new PushBlobRunnable(this)))) {
         MOZ_ASSERT(false, "NS_DispatchToMainThread PushBlobRunnable failed");
       } else {
         mLastBlobTimeStamp = TimeStamp::Now();
       }
     }
   }
 
-  // Bind media source with MediaEncoder to receive raw media data.
-  void SetupStreams()
-  {
-    MOZ_ASSERT(NS_IsMainThread());
-
-    // Create a Track Union Stream
-    MediaStreamGraph* gm = mRecorder->GetSourceMediaStream()->Graph();
-    mTrackUnionStream = gm->CreateTrackUnionStream(nullptr);
-    MOZ_ASSERT(mTrackUnionStream, "CreateTrackUnionStream failed");
-
-    mTrackUnionStream->SetAutofinish(true);
-
-    // Bind this Track Union Stream with Source Media.
-    mInputPort = mTrackUnionStream->AllocateInputPort(mRecorder->GetSourceMediaStream());
-
-    DOMMediaStream* domStream = mRecorder->Stream();
-    if (domStream) {
-      // Get the track type hint from DOM media stream.
-      TracksAvailableCallback* tracksAvailableCallback = new TracksAvailableCallback(this);
-      domStream->OnTracksAvailable(tracksAvailableCallback);
-    } else {
-      // Web Audio node has only audio.
-      InitEncoder(ContainerWriter::CREATE_AUDIO_TRACK);
-    }
-  }
-
   bool CheckPermission(const char* aType)
   {
     nsCOMPtr<nsIDocument> doc = mRecorder->GetOwner()->GetExtantDoc();
     if (!doc) {
       return false;
     }
 
     uint16_t appStatus = nsIPrincipal::APP_STATUS_NOT_INSTALLED;