Add license header.

Change-Id: I2e5458f4aed7da1890e268b933b89543ee6c6013

cmd/gitfs-populate/main_test.go

diff --git a/cmd/gitfs-populate/main_test.go b/cmd/gitfs-populate/main_test.go
index f1eabd1..63f494b 100644
--- a/cmd/gitfs-populate/main_test.go
+++ b/cmd/gitfs-populate/main_test.go
@@ -1,3 +1,17 @@
+// Copyright 2016 Google Inc. All rights reserved.
+//
+// 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 main
 
 import (