Separate mojo/shell into a runner and the application manager (shell)

mojo/shell/identity.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_IDENTITY_H_
-#define SHELL_APPLICATION_MANAGER_IDENTITY_H_
+#ifndef MOJO_SHELL_IDENTITY_H_
+#define MOJO_SHELL_IDENTITY_H_
 
 #include "url/gurl.h"
 
 namespace mojo {
 namespace shell {
 
 /**
  * Represents the identity of an application. |url| is the url of the
  * application. |qualifier| is a string that allows to tie a specific instance
  * of an application to another. It is used by content handlers that need to be
  * run in the context of another application.
  */
 struct Identity {
   Identity(const GURL& url, const std::string& qualifier);
   explicit Identity(const GURL& url);
   bool operator<(const Identity& other) const;
 
   const GURL url;
   const std::string qualifier;
 };
 
 }  // namespace shell
 }  // namespace mojo
 
-#endif  // SHELL_APPLICATION_MANAGER_IDENTITY_H_
+#endif  // MOJO_SHELL_IDENTITY_H_