First cut at "content handling" support in Mojo.

mojo/shell/switches.cc

 // Copyright 2013 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.
 
 #include "mojo/shell/switches.h"
 
 namespace switches {
 
 // Used to specify the type of child process (switch values from
 // |ChildProcess::Type|).
 const char kChildProcessType[] = "child-process-type";
 
+// Comma separated list like:
+// text/html,mojo://mojo_html_viewer,application/bravo,https://abarth.com/bravo
+const char kContentHandlers[] = "content-handlers";
+
 // Force dynamically loaded apps / services to be loaded irrespective of cache
 // instructions.
 const char kDisableCache[] = "disable-cache";
 
 // Load apps in separate processes.
 // TODO(vtl): Work in progress; doesn't work. Flip this to "disable" (or maybe
 // change it to "single-process") when it works.
 const char kEnableMultiprocess[] = "enable-multiprocess";
 
 // Map mojo: URLs to a shared library of similar name at this origin. See
 // mojo_url_resolver.cc for details.
 const char kOrigin[] = "origin";
 
 // Enables the mojo spy, which acts as a man-in-the-middle inspector for
 // message pipes and other activities. This is work in progress.
 const char kSpy[] = "spy";
 
 }  // namespace switches