Add auto-indenting for .mojom files in VIM

tools/vim/mojom/indent/mojom.vim

Index: tools/vim/mojom/indent/mojom.vim
diff --git a/tools/vim/mojom/indent/mojom.vim b/tools/vim/mojom/indent/mojom.vim
new file mode 100644
index 0000000000000000000000000000000000000000..77a9b9fea618b3a106c93e80e500b77b8c132dd0
--- /dev/null
+++ b/tools/vim/mojom/indent/mojom.vim
@@ -0,0 +1,15 @@
+" Copyright 2015 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.
+" Vim syntax file " Language: Mojom
+" To get syntax highlighting for .mojom files, add the following to your .vimrc
+" file:
+"     set runtimepath^=/path/to/src/tools/vim/mojom
+
+if exists("b:did_indent")
+   finish
+endif
+let b:did_indent = 1
+
+setlocal cindent
+setlocal formatoptions=tcroq