Close all writers before JingleSession is destroyed.

remoting/protocol/video_writer.h

Index: remoting/protocol/video_writer.h
diff --git a/remoting/protocol/video_writer.h b/remoting/protocol/video_writer.h
index b9216c05dc7bd4720743b636456b11026ba49f7f..be4c715c01468b5c26323d6bed46a13a2d616362 100644
--- a/remoting/protocol/video_writer.h
+++ b/remoting/protocol/video_writer.h
@@ -19,7 +19,6 @@ namespace protocol {
 class Session;
 class SessionConfig;
 
-// TODO(sergeyu): VideoWriter should implement VideoStub interface.
 class VideoWriter : public VideoStub {
  public:
   virtual ~VideoWriter();
@@ -29,6 +28,10 @@ class VideoWriter : public VideoStub {
   // Initializes the writer.
   virtual void Init(Session* session) = 0;
 
+  // Stops writing. Must be called on the network thread before this
+  // object is destroyed.
+  virtual void Close() = 0;
+
  protected:
   VideoWriter() { }