milo: Add barebones BuildInfo pRPC service.

milo/appengine/buildinfo/service.go

Index: milo/appengine/buildinfo/service.go
diff --git a/milo/appengine/buildinfo/service.go b/milo/appengine/buildinfo/service.go
new file mode 100644
index 0000000000000000000000000000000000000000..12ddb21b6bf8c740c16e338dfaea81d906a51b7a
--- /dev/null
+++ b/milo/appengine/buildinfo/service.go
@@ -0,0 +1,41 @@
+// Copyright 2017 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package buildinfo
+
+import (
+	"github.com/luci/luci-go/grpc/grpcutil"
+	"github.com/luci/luci-go/luci_config/common/cfgtypes"
+	milo "github.com/luci/luci-go/milo/api/proto"
+
+	"google.golang.org/grpc/codes"
+
+	"golang.org/x/net/context"
+)
+
+// Service is a BuildInfoServer implementation.
+type Service struct{}
+
+var _ milo.BuildInfoServer = (*Service)(nil)
+
+// Get implements milo.BuildInfoServer.
+func (svc *Service) Get(c context.Context, req *milo.BuildInfoRequest) (*milo.BuildInfoResponse, error) {
+	projectHint := cfgtypes.ProjectName(req.ProjectHint)
+	if projectHint != "" {
+		if err := projectHint.Validate(); err != nil {
+			return nil, grpcutil.Errf(codes.InvalidArgument, "invalid project hint: %s", err.Error())
+		}
+	}
+
+	switch {
+	case req.GetBuildbot() != nil:
+		return nil, grpcutil.Unimplemented
+
+	case req.GetSwarming() != nil:
+		return nil, grpcutil.Unimplemented
+
+	default:
+		return nil, grpcutil.Unimplemented
+	}
+}