token-server: Add protos for new API for generating service account tokens.

server/auth/delegation.go

 // Copyright 2016 The LUCI 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 auth
 
 import (
         "fmt"
         "net/http"
         "strings"
         "time"
 
+        "google.golang.org/grpc"
+
         "golang.org/x/net/context"
 
         "github.com/luci/luci-go/common/clock"
         "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/common/retry"
         "github.com/luci/luci-go/common/retry/transient"
         "github.com/luci/luci-go/grpc/grpcutil"
         "github.com/luci/luci-go/grpc/prpc"
         "github.com/luci/luci-go/server/auth/delegation"
         "github.com/luci/luci-go/server/auth/delegation/messages"
@@ skipping 65 matching lines @@
         //
         // Used only for logging purposes on the auth service, will be indexed. Should
         // be a short identifier-like string.
         //
         // Optional.
         Intent string
 
         // rpcClient is token server RPC client to use.
         //
         // Mocked in tests.
-        rpcClient minter.TokenMinterClient
+        rpcClient tokenMinterClient
+}
+
+// tokenMinterClient is subset of minter.TokenMinterClient we use.
+type tokenMinterClient interface {
+        MintDelegationToken(context.Context, *minter.MintDelegationTokenRequest, ...grpc.CallOption) (*minter.MintDelegationTokenResponse, error)
 }
 
 // delegationTokenCache is used to store delegation tokens in the cache.
 //
 // The underlying token type is delegation.Token.
 var delegationTokenCache = tokenCache{
         Kind:                "delegation",
         Version:             3,
         ExpRandPercent:      10,
         MinAcceptedLifetime: 5 * time.Minute,
@@ skipping 171 matching lines @@
 
         if err != nil {
                 report(err, label)
                 return nil, err
         }
 
         t := cached.Token.(delegation.Token) // let it panic on type mismatch
         report(nil, label)
         return &t, nil
 }