Use WeakPtrFactory in net::BidirectionalStream when posting task

net/http/bidirectional_stream.h

Index: net/http/bidirectional_stream.h
diff --git a/net/http/bidirectional_stream.h b/net/http/bidirectional_stream.h
index 95e7f2e90f3b1cc243900cbb11904d9eae666f3f..488b88eb1a27e3f09247238d2842f45154f16ab8 100644
--- a/net/http/bidirectional_stream.h
+++ b/net/http/bidirectional_stream.h
@@ -216,6 +216,9 @@ class NET_EXPORT BidirectionalStream
                                   HttpStream* stream) override;
   void OnQuicBroken() override;
 
+  // Helper method to notify delegate if there is an error.
+  void NotifyError(int error);
+
   // BidirectionalStreamRequestInfo used when requesting the stream.
   std::unique_ptr<BidirectionalStreamRequestInfo> request_info_;
   const BoundNetLog net_log_;
@@ -246,6 +249,8 @@ class NET_EXPORT BidirectionalStream
   // List of buffer length.
   std::vector<int> write_buffer_len_list_;
 
+  base::WeakPtrFactory<BidirectionalStream> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(BidirectionalStream);
 };