Enables specifying mojo url mapping on command line

mojo/shell/mojo_url_resolver.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 MOJO_SHELL_MOJO_URL_RESOLVER_H_
 #define MOJO_SHELL_MOJO_URL_RESOLVER_H_
 
 #include <map>
 #include <set>
 
+#include "base/basictypes.h"
 #include "url/gurl.h"
 
 namespace mojo {
 namespace shell {
 
 // This class resolves "mojo:" URLs to physical URLs (e.g., "file:" and
 // "https:" URLs). By default, "mojo:" URLs resolve to a file location, but
 // that resolution can be customized via the AddCustomMapping method.
 class MojoURLResolver {
  public:
   MojoURLResolver();
   ~MojoURLResolver();
 
   // If specified, then unknown "mojo:" URLs will be resolved relative to this
   // base URL. That is, the portion after the colon will be appeneded to
   // |base_url| with platform-specific shared library prefix and suffix
   // inserted.
   void SetBaseURL(const GURL& base_url);
 
-  // Add a custom mapping for a particular "mojo:" URL.
+  // Add a custom mapping for a particular "mojo:" URL. If |resolved_url| is
+  // itself a mojo url normal resolution rules apply.
   void AddCustomMapping(const GURL& mojo_url, const GURL& resolved_url);
 
   // Add a local file mapping for a particular "mojo:" URL. This causes the
   // "mojo:" URL to be resolved to a base::DIR_MODULE-relative shared library.
   void AddLocalFileMapping(const GURL& mojo_url);
 
   // Resolve the given "mojo:" URL to the URL that should be used to fetch the
   // code for the corresponding Mojo App.
   GURL Resolve(const GURL& mojo_url) const;
 
  private:
+  // Applies all custom mappings for |url|, returning the last non-mapped url.
+  // For example, if 'a' maps to 'b' and 'b' maps to 'c' calling this with 'a'
+  // returns 'c'.
+  GURL ApplyCustomMappings(const GURL& url) const;
+
   std::map<GURL, GURL> url_map_;
   std::set<GURL> local_file_set_;
   GURL default_base_url_;
   GURL base_url_;
+
+  DISALLOW_COPY_AND_ASSIGN(MojoURLResolver);
 };
 
 }  // namespace shell
 }  // namespace mojo
 
 #endif  // MOJO_SHELL_MOJO_URL_RESOLVER_H_