Remove direct dependency of futures-core.

Author: davidli2010

Cargo.toml

@@ -12,8 +12,7 @@ keywords = ["etcd", "v3", "api", "client", "async"]
 [dependencies]
 tonic = "0.1"
 prost = "0.6"
-tokio = { version = "0.2", features = ["rt-core", "stream", "sync"] }
-futures-core = "0.3"
+tokio = { version = "0.2", features = ["stream"] }
 http = "0.2"
 
 [dev-dependencies]

src/rpc/watch.rs

@@ -11,8 +11,8 @@ use crate::rpc::pb::etcdserverpb::{
 };
 use crate::rpc::pb::mvccpb::Event as PbEvent;
 use crate::rpc::{get_prefix, KeyValue, ResponseHeader};
-use futures_core::task::{Context, Poll};
-use futures_core::Stream;
+use std::task::{Context, Poll};
+use tokio::stream::Stream;
 use tokio::sync::mpsc::{channel, Sender};
 use tonic::codegen::Pin;
 use tonic::transport::Channel;