clang-format: Allow .proto files to be formatted (supported by an upcoming binary/script; this change is safe if you are running an older binary); remove warnings.

BUG=344916

Review URL: https://codereview.chromium.org/177213013

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@253295 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/git_cl.py b/git_cl.py
index 1d3d24c..ef883e1 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -2299,7 +2299,7 @@
 @subcommand.usage('[files or directories to diff]')
 def CMDformat(parser, args):
   """Runs clang-format on the diff."""
-  CLANG_EXTS = ['.cc', '.cpp', '.h', '.mm']
+  CLANG_EXTS = ['.cc', '.cpp', '.h', '.mm', '.proto']
   parser.add_option('--full', action='store_true',
                     help='Reformat the full content of all touched files')
   parser.add_option('--dry-run', action='store_true',