Deprecate instead of close SPDY sessions upon network change.

net/spdy/spdy_session.h

Index: net/spdy/spdy_session.h
diff --git a/net/spdy/spdy_session.h b/net/spdy/spdy_session.h
index fde42024be8f54291338e01b246d797af7212f7c..0e28156bbacd20eca1ffeca95c6dd778738e2e3a 100644
--- a/net/spdy/spdy_session.h
+++ b/net/spdy/spdy_session.h
@@ -353,6 +353,10 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
   // |description| indicates the reason for the error.
   void CloseSessionOnError(Error err, const std::string& description);
 
+  // Mark this session as going away. It will not be used to service new
+  // streams.
+  void Deprecate();
+
   // Retrieves information on the current state of the SPDY session as a
   // Value.  Caller takes possession of the returned value.
   base::Value* GetInfoAsValue() const;