LogDog: Add prefix registration endpoint.

appengine/logdog/coordinator/endpoints/registration/registerPrefix.go

Index: appengine/logdog/coordinator/endpoints/registration/registerPrefix.go
diff --git a/appengine/logdog/coordinator/endpoints/registration/registerPrefix.go b/appengine/logdog/coordinator/endpoints/registration/registerPrefix.go
new file mode 100644
index 0000000000000000000000000000000000000000..41b02d9e5127a0debab8a45af85adc4824803e77
--- /dev/null
+++ b/appengine/logdog/coordinator/endpoints/registration/registerPrefix.go
@@ -0,0 +1,16 @@
+// 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 registration
+
+import (
+	"github.com/luci/luci-go/common/api/logdog_coordinator/registration/v1"
+	"github.com/luci/luci-go/common/grpcutil"
+	"golang.org/x/net/context"
+)
+
+func (s *server) RegisterPrefix(c context.Context, req *logdog.RegisterPrefixRequest) (*logdog.RegisterPrefixResponse, error) {
+	// TODO(dnj): Actually implement this endpoint.
+	return nil, grpcutil.Unimplemented
+}