diff --git a/vendor/google.golang.org/grpc/pickfirst.go b/vendor/google.golang.org/grpc/pickfirst.go
new file mode 100644
index 0000000..f194d14
--- /dev/null
+++ b/vendor/google.golang.org/grpc/pickfirst.go
@@ -0,0 +1,155 @@
+/*
+ *
+ * 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 (
+	"errors"
+	"fmt"
+
+	"google.golang.org/grpc/balancer"
+	"google.golang.org/grpc/connectivity"
+)
+
+// PickFirstBalancerName is the name of the pick_first balancer.
+const PickFirstBalancerName = "pick_first"
+
+func newPickfirstBuilder() balancer.Builder {
+	return &pickfirstBuilder{}
+}
+
+type pickfirstBuilder struct{}
+
+func (*pickfirstBuilder) Build(cc balancer.ClientConn, opt balancer.BuildOptions) balancer.Balancer {
+	return &pickfirstBalancer{cc: cc}
+}
+
+func (*pickfirstBuilder) Name() string {
+	return PickFirstBalancerName
+}
+
+type pickfirstBalancer struct {
+	state connectivity.State
+	cc    balancer.ClientConn
+	sc    balancer.SubConn
+}
+
+func (b *pickfirstBalancer) ResolverError(err error) {
+	switch b.state {
+	case connectivity.TransientFailure, connectivity.Idle, connectivity.Connecting:
+		// Set a failing picker if we don't have a good picker.
+		b.cc.UpdateState(balancer.State{ConnectivityState: connectivity.TransientFailure,
+			Picker: &picker{err: fmt.Errorf("name resolver error: %v", err)},
+		})
+	}
+	if logger.V(2) {
+		logger.Infof("pickfirstBalancer: ResolverError called with error %v", err)
+	}
+}
+
+func (b *pickfirstBalancer) UpdateClientConnState(cs balancer.ClientConnState) error {
+	if len(cs.ResolverState.Addresses) == 0 {
+		b.ResolverError(errors.New("produced zero addresses"))
+		return balancer.ErrBadResolverState
+	}
+	if b.sc == nil {
+		var err error
+		b.sc, err = b.cc.NewSubConn(cs.ResolverState.Addresses, balancer.NewSubConnOptions{})
+		if err != nil {
+			if logger.V(2) {
+				logger.Errorf("pickfirstBalancer: failed to NewSubConn: %v", err)
+			}
+			b.state = connectivity.TransientFailure
+			b.cc.UpdateState(balancer.State{ConnectivityState: connectivity.TransientFailure,
+				Picker: &picker{err: fmt.Errorf("error creating connection: %v", err)},
+			})
+			return balancer.ErrBadResolverState
+		}
+		b.state = connectivity.Idle
+		b.cc.UpdateState(balancer.State{ConnectivityState: connectivity.Idle, Picker: &picker{result: balancer.PickResult{SubConn: b.sc}}})
+		b.sc.Connect()
+	} else {
+		b.cc.UpdateAddresses(b.sc, cs.ResolverState.Addresses)
+		b.sc.Connect()
+	}
+	return nil
+}
+
+func (b *pickfirstBalancer) UpdateSubConnState(sc balancer.SubConn, s balancer.SubConnState) {
+	if logger.V(2) {
+		logger.Infof("pickfirstBalancer: UpdateSubConnState: %p, %v", sc, s)
+	}
+	if b.sc != sc {
+		if logger.V(2) {
+			logger.Infof("pickfirstBalancer: ignored state change because sc is not recognized")
+		}
+		return
+	}
+	b.state = s.ConnectivityState
+	if s.ConnectivityState == connectivity.Shutdown {
+		b.sc = nil
+		return
+	}
+
+	switch s.ConnectivityState {
+	case connectivity.Ready:
+		b.cc.UpdateState(balancer.State{ConnectivityState: s.ConnectivityState, Picker: &picker{result: balancer.PickResult{SubConn: sc}}})
+	case connectivity.Connecting:
+		b.cc.UpdateState(balancer.State{ConnectivityState: s.ConnectivityState, Picker: &picker{err: balancer.ErrNoSubConnAvailable}})
+	case connectivity.Idle:
+		b.cc.UpdateState(balancer.State{ConnectivityState: s.ConnectivityState, Picker: &idlePicker{sc: sc}})
+	case connectivity.TransientFailure:
+		b.cc.UpdateState(balancer.State{
+			ConnectivityState: s.ConnectivityState,
+			Picker:            &picker{err: s.ConnectionError},
+		})
+	}
+}
+
+func (b *pickfirstBalancer) Close() {
+}
+
+func (b *pickfirstBalancer) ExitIdle() {
+	if b.state == connectivity.Idle {
+		b.sc.Connect()
+	}
+}
+
+type picker struct {
+	result balancer.PickResult
+	err    error
+}
+
+func (p *picker) Pick(info balancer.PickInfo) (balancer.PickResult, error) {
+	return p.result, p.err
+}
+
+// idlePicker is used when the SubConn is IDLE and kicks the SubConn into
+// CONNECTING when Pick is called.
+type idlePicker struct {
+	sc balancer.SubConn
+}
+
+func (i *idlePicker) Pick(info balancer.PickInfo) (balancer.PickResult, error) {
+	i.sc.Connect()
+	return balancer.PickResult{}, balancer.ErrNoSubConnAvailable
+}
+
+func init() {
+	balancer.Register(newPickfirstBuilder())
+}