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

shell/application_manager/shell_impl.h

 // 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.
 
 #ifndef SHELL_APPLICATION_MANAGER_SHELL_IMPL_H_
 #define SHELL_APPLICATION_MANAGER_SHELL_IMPL_H_
 
 #include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/error_handler.h"
 #include "mojo/public/interfaces/application/application.mojom.h"
 #include "mojo/public/interfaces/application/shell.mojom.h"
 #include "url/gurl.h"
 
 namespace mojo {
+namespace shell {
+
 class ApplicationManager;
 
 class ShellImpl : public Shell, public ErrorHandler {
  public:
   ShellImpl(ApplicationPtr application,
             ApplicationManager* manager,
             // The original URL that was first requested, before any resolution.
             const GURL& original_url,
             const GURL& resolved_url);
 
@@ skipping 21 matching lines @@
 
   ApplicationManager* const manager_;
   const GURL requested_url_;
   const GURL url_;
   ApplicationPtr application_;
   Binding<Shell> binding_;
 
   DISALLOW_COPY_AND_ASSIGN(ShellImpl);
 };
 
+}  // namespace shell
 }  // namespace mojo
 
 #endif  // SHELL_APPLICATION_MANAGER_SHELL_IMPL_H_