Formatter: Avoid extraneous empty lines at the end of a block.

mojom/mojom_parser/formatter/formatter_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 formatter
 
 import (
         "strings"
         "testing"
 )
@@ skipping 91 matching lines @@
 
         actual, err := FormatMojom("test.mojom", original)
         if err != nil {
                 t.Fatalf("Parser was not supposed to fail: %s", err.Error())
         }
 
         if original != actual {
                 t.Fatalf("\nExpected:\n%v\n\n*****\n\nActual:\n%v eof", original, actual)
         }
 }
+
+func TestFormatNoExtraFinalBlankLine(t *testing.T) {
+        original := `interface ImagePipe {
+  // Some comment.
+  FlushImages();
+
+};
+`
+
+        expected := `interface ImagePipe {
+  // Some comment.
+  FlushImages();
+};
+`
+        actual, err := FormatMojom("test.mojom", original)
+        if err != nil {
+                t.Fatalf("Parser was not supposed to fail: %s", err.Error())
+        }
+
+        if expected != actual {
+                t.Fatalf("\nExpected:\n%v\n\n*****\n\nActual:\n%v eof", expected, actual)
+        }
+}