Use the mojo::shell namespace consistently underly shell/.

shell/filename_util.h

 // 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.
 
 #ifndef SHELL_FILENAME_UTIL_H_
 #define SHELL_FILENAME_UTIL_H_
 
 class GURL;
 
 namespace base {
 class FilePath;
 }
 
 namespace mojo {
+namespace shell {
 
 // Given the full path to a file name, creates a file: URL. The returned URL
 // may not be valid if the input is malformed.
 GURL FilePathToFileURL(const base::FilePath& path);
 
 // This URL is going to be treated as a directory. Ensure there is a trailing
 // slash so that GURL.Resolve(...) works correctly.
 GURL AddTrailingSlashIfNeeded(const GURL& url);
 
+}  // namespace shell
 }  // namespace mojo
 
 #endif  // SHELL_FILENAME_UTIL_H_