diff --git a/go/vendor/google.golang.org/grpc/resolver_conn_wrapper.go b/go/vendor/google.golang.org/grpc/resolver_conn_wrapper.go
new file mode 100644
index 0000000..a6c02ac
--- /dev/null
+++ b/go/vendor/google.golang.org/grpc/resolver_conn_wrapper.go
@@ -0,0 +1,189 @@
+/*
+ *
+ * Copyright 2017 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpc
+
+import (
+	"fmt"
+	"strings"
+
+	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/internal/channelz"
+	"google.golang.org/grpc/resolver"
+)
+
+// ccResolverWrapper is a wrapper on top of cc for resolvers.
+// It implements resolver.ClientConnection interface.
+type ccResolverWrapper struct {
+	cc                 *ClientConn
+	resolver           resolver.Resolver
+	addrCh             chan []resolver.Address
+	scCh               chan string
+	done               chan struct{}
+	lastAddressesCount int
+}
+
+// split2 returns the values from strings.SplitN(s, sep, 2).
+// If sep is not found, it returns ("", s, false) instead.
+func split2(s, sep string) (string, string, bool) {
+	spl := strings.SplitN(s, sep, 2)
+	if len(spl) < 2 {
+		return "", "", false
+	}
+	return spl[0], spl[1], true
+}
+
+// parseTarget splits target into a struct containing scheme, authority and
+// endpoint.
+//
+// If target is not a valid scheme://authority/endpoint, it returns {Endpoint:
+// target}.
+func parseTarget(target string) (ret resolver.Target) {
+	var ok bool
+	ret.Scheme, ret.Endpoint, ok = split2(target, "://")
+	if !ok {
+		return resolver.Target{Endpoint: target}
+	}
+	ret.Authority, ret.Endpoint, ok = split2(ret.Endpoint, "/")
+	if !ok {
+		return resolver.Target{Endpoint: target}
+	}
+	return ret
+}
+
+// newCCResolverWrapper parses cc.target for scheme and gets the resolver
+// builder for this scheme and builds the resolver. The monitoring goroutine
+// for it is not started yet and can be created by calling start().
+//
+// If withResolverBuilder dial option is set, the specified resolver will be
+// used instead.
+func newCCResolverWrapper(cc *ClientConn) (*ccResolverWrapper, error) {
+	rb := cc.dopts.resolverBuilder
+	if rb == nil {
+		return nil, fmt.Errorf("could not get resolver for scheme: %q", cc.parsedTarget.Scheme)
+	}
+
+	ccr := &ccResolverWrapper{
+		cc:     cc,
+		addrCh: make(chan []resolver.Address, 1),
+		scCh:   make(chan string, 1),
+		done:   make(chan struct{}),
+	}
+
+	var err error
+	ccr.resolver, err = rb.Build(cc.parsedTarget, ccr, resolver.BuildOption{DisableServiceConfig: cc.dopts.disableServiceConfig})
+	if err != nil {
+		return nil, err
+	}
+	return ccr, nil
+}
+
+func (ccr *ccResolverWrapper) start() {
+	go ccr.watcher()
+}
+
+// watcher processes address updates and service config updates sequentially.
+// Otherwise, we need to resolve possible races between address and service
+// config (e.g. they specify different balancer types).
+func (ccr *ccResolverWrapper) watcher() {
+	for {
+		select {
+		case <-ccr.done:
+			return
+		default:
+		}
+
+		select {
+		case addrs := <-ccr.addrCh:
+			select {
+			case <-ccr.done:
+				return
+			default:
+			}
+			grpclog.Infof("ccResolverWrapper: sending new addresses to cc: %v", addrs)
+			if channelz.IsOn() {
+				ccr.addChannelzTraceEvent(addrs)
+			}
+			ccr.cc.handleResolvedAddrs(addrs, nil)
+		case sc := <-ccr.scCh:
+			select {
+			case <-ccr.done:
+				return
+			default:
+			}
+			grpclog.Infof("ccResolverWrapper: got new service config: %v", sc)
+			ccr.cc.handleServiceConfig(sc)
+		case <-ccr.done:
+			return
+		}
+	}
+}
+
+func (ccr *ccResolverWrapper) resolveNow(o resolver.ResolveNowOption) {
+	ccr.resolver.ResolveNow(o)
+}
+
+func (ccr *ccResolverWrapper) close() {
+	ccr.resolver.Close()
+	close(ccr.done)
+}
+
+// NewAddress is called by the resolver implemenetion to send addresses to gRPC.
+func (ccr *ccResolverWrapper) NewAddress(addrs []resolver.Address) {
+	select {
+	case <-ccr.addrCh:
+	default:
+	}
+	ccr.addrCh <- addrs
+}
+
+// NewServiceConfig is called by the resolver implemenetion to send service
+// configs to gRPC.
+func (ccr *ccResolverWrapper) NewServiceConfig(sc string) {
+	select {
+	case <-ccr.scCh:
+	default:
+	}
+	ccr.scCh <- sc
+}
+
+func (ccr *ccResolverWrapper) addChannelzTraceEvent(addrs []resolver.Address) {
+	if len(addrs) == 0 && ccr.lastAddressesCount != 0 {
+		channelz.AddTraceEvent(ccr.cc.channelzID, &channelz.TraceEventDesc{
+			Desc:     "Resolver returns an empty address list",
+			Severity: channelz.CtWarning,
+		})
+	} else if len(addrs) != 0 && ccr.lastAddressesCount == 0 {
+		var s string
+		for i, a := range addrs {
+			if a.ServerName != "" {
+				s += a.Addr + "(" + a.ServerName + ")"
+			} else {
+				s += a.Addr
+			}
+			if i != len(addrs)-1 {
+				s += " "
+			}
+		}
+		channelz.AddTraceEvent(ccr.cc.channelzID, &channelz.TraceEventDesc{
+			Desc:     fmt.Sprintf("Resolver returns a non-empty address list (previous one was empty) %q", s),
+			Severity: channelz.CtINFO,
+		})
+	}
+	ccr.lastAddressesCount = len(addrs)
+}