mojom: Remove braces from module statements and make them come first.

mojo/services/public/interfaces/navigation/navigation.mojom

 // Copyright 2014 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 mojo;
+
 import "mojo/services/public/interfaces/network/url_loader.mojom";
 
-module mojo {
-
 // Expresses a preference for where a navigation will be performed.
 enum Target {
   // No preference
   DEFAULT,
 
   // In the same ViewManager node that the navigation was initiated
   SOURCE_NODE,
 
   // In a new ViewManager node
   NEW_NODE
 };
 
 // Embedders that support navigation of implement this interface.
 interface NavigatorHost {
   RequestNavigate(Target target, URLRequest request);
 
   // Applications call this to inform hosts of navigations they performed
   // locally. For example, pushState() navigations in an HTML application.
   DidNavigateLocally(string url);
 };
-
-}