Revert of Migrate tsmon protos to proto3

common/tsmon/field/field.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package field
 
 import (
         "fmt"
 
+        "github.com/golang/protobuf/proto"
+
         pb "github.com/luci/luci-go/common/tsmon/ts_mon_proto"
 )
 
 // Field is the definition of a metric field.  It has a name and a type
 // (string, int or bool).
 type Field struct {
         Name string
         Type pb.MetricsField_FieldType
 }
 
@@ skipping 11 matching lines @@
 // stored as int64s.
 func Int(name string) Field { return Field{name, pb.MetricsField_INT} }
 
 // Serialize returns a slice of ts_mon_proto.MetricsField messages representing
 // the field names, types and values.
 func Serialize(fields []Field, values []interface{}) []*pb.MetricsField {
         ret := make([]*pb.MetricsField, len(fields))
 
         for i, f := range fields {
                 d := &pb.MetricsField{
-                        Name: f.Name,
-                        Type: f.Type,
+                        Name: proto.String(f.Name),
+                        Type: f.Type.Enum(),
                 }
 
                 switch f.Type {
                 case pb.MetricsField_STRING:
-                        d.StringValue = values[i].(string)
+                        d.StringValue = proto.String(values[i].(string))
                 case pb.MetricsField_BOOL:
-                        d.BoolValue = values[i].(bool)
+                        d.BoolValue = proto.Bool(values[i].(bool))
                 case pb.MetricsField_INT:
-                        d.IntValue = values[i].(int64)
+                        d.IntValue = proto.Int64(values[i].(int64))
                 }
 
                 ret[i] = d
         }
 
         return ret
 }