Add module suffix in .mojom files for components/arc

components/arc/common/auth.mojom

 // 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.
 
-module arc;
+module arc.mojom;
 
 // These values describe failure reason of sign-in.
 enum ArcSignInFailureReason {
   UNKNOWN_ERROR = 0,
   NETWORK_ERROR = 1,
   SERVICE_UNAVAILABLE = 2,
   BAD_AUTHENTICATION = 3,
   GMS_CORE_NOT_AVAILABLE = 4,
   CLOUD_PROVISION_FLOW_FAIL = 5,
 };
@@ skipping 10 matching lines @@
   [MinVersion=2] OnSignInComplete@2();
   // Notifies Chrome that the sign-in fails to complete and provides failure
   // reason.
   [MinVersion=2] OnSignInFailed@3(ArcSignInFailureReason reason);
 };
 
 interface AuthInstance {
   // Establishes full-duplex communication with the host.
   Init(AuthHost host_ptr);
 };