Revert "Remove dead members of server context"

This reverts commit 8c8588c7dc047ee509c7367f61ba0c5f00cb61d1.
diff --git a/include/grpc++/server_context.h b/include/grpc++/server_context.h
index 36cbae8..9e3b80c 100644
--- a/include/grpc++/server_context.h
+++ b/include/grpc++/server_context.h
@@ -78,6 +78,8 @@
   void AddInitialMetadata(const grpc::string& key, const grpc::string& value);
   void AddTrailingMetadata(const grpc::string& key, const grpc::string& value);
 
+  bool IsCancelled();
+
   const std::multimap<grpc::string, grpc::string>& client_metadata() {
     return client_metadata_;
   }
@@ -110,6 +112,7 @@
 
   std::chrono::system_clock::time_point deadline_;
   grpc_call* call_;
+  CompletionQueue* cq_;
   bool sent_initial_metadata_;
   std::multimap<grpc::string, grpc::string> client_metadata_;
   std::multimap<grpc::string, grpc::string> initial_metadata_;