Use unique URLs rather than qualifiers to uniquify RenderProcesses.

mojo/shell/application_manager.mojom

 // 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.
 
 module mojo.shell.mojom;
 
 interface ApplicationManager {
   // Instructs the ApplicationManager to create an instance for an existing
   // process at the other end of |channel|, and perform applicable
   // initialization. This assumes the target process will bind the other end of
   // channel to an implementation of ChildController and bind an Application
   // request there.
   // TODO(beng): we should probably have an Identity mojom struct.
   // TODO(beng): for this to be used in production, it's going to have to take
   //             a fully qualified Identity complete with CapabilityFilter,
   //             otherwise child processes registered with the shell will be
   //             able to request any application/service.
   //             http://crbug.com/555392
-  CreateInstanceForHandle(handle channel, string url, string qualifier);
+  CreateInstanceForHandle(handle channel, string url);
 };