Revert of Migrate tsmon protos to proto3

appengine/tsmon/global_callback_test.go

 // Copyright 2016 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 tsmon
 
 import (
         "net/http"
         "net/http/httptest"
         "testing"
         "time"
 
+        "github.com/golang/protobuf/proto"
         "github.com/julienschmidt/httprouter"
         "github.com/luci/gae/service/datastore"
         "github.com/luci/luci-go/common/clock/testclock"
         "github.com/luci/luci-go/common/tsmon"
         "github.com/luci/luci-go/common/tsmon/metric"
         "github.com/luci/luci-go/common/tsmon/monitor"
         "github.com/luci/luci-go/common/tsmon/store"
         "github.com/luci/luci-go/common/tsmon/target"
         "golang.org/x/net/context"
 
@@ skipping 21 matching lines @@
         c := context.Background()
 
         Convey("Register callback without metrics panics", t, func() {
                 So(func() {
                         RegisterGlobalCallbackIn(c, func(context.Context) {})
                 }, ShouldPanic)
         })
 
         Convey("Global callbacks", t, func() {
                 c, clock := buildGAETestContext()
-                s := store.NewInMemory(&target.Task{ServiceName: "default target"})
+                s := store.NewInMemory(&target.Task{ServiceName: proto.String("default target")})
                 mon := &monitor.Fake{}
                 state := tsmon.GetState(c)
                 state.S = s
                 state.M = mon
                 m := metric.NewCallbackStringIn(c, "foo", "")
 
                 RegisterGlobalCallbackIn(c, func(c context.Context) {
                         m.Set(c, "bar")
                 }, m)
 
@@ skipping 20 matching lines @@
                                 So(err, ShouldBeNil)
                                 So(val, ShouldBeNil)
 
                                 So(len(mon.Cells), ShouldEqual, 1)
                                 So(len(mon.Cells[0]), ShouldEqual, 1)
                                 So(mon.Cells[0][0].Value, ShouldEqual, "bar")
                         })
                 })
         })
 }