make load balancing policy name string case-insensitive (#1708)

balancer/balancer.go

@@ -23,6 +23,7 @@ package balancer
 import (
 	"errors"
 	"net"
+	"strings"
 
 	"golang.org/x/net/context"
 	"google.golang.org/grpc/connectivity"
@@ -36,15 +37,17 @@ var (
 )
 
 // Register registers the balancer builder to the balancer map.
-// b.Name will be used as the name registered with this builder.
+// b.Name (lowercased) will be used as the name registered with
+// this builder.
 func Register(b Builder) {
-	m[b.Name()] = b
+	m[strings.ToLower(b.Name())] = b
 }
 
 // Get returns the resolver builder registered with the given name.
+// Note that the compare is done in a case-insenstive fashion.
 // If no builder is register with the name, nil will be returned.
 func Get(name string) Builder {
-	if b, ok := m[name]; ok {
+	if b, ok := m[strings.ToLower(name)]; ok {
 		return b
 	}
 	return nil

clientconn.go

@@ -689,7 +689,7 @@ func (cc *ClientConn) switchBalancer(name string) {
 		return
 	}
 
-	if cc.curBalancerName == name {
+	if strings.ToLower(cc.curBalancerName) == strings.ToLower(name) {
 		return
 	}