Turn 'browser' app into a 'launcher_ui' app that window_manager embeds.

mojo/services/public/interfaces/launcher/launcher.mojom

 // 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.
 
 import "../network/url_loader.mojom"
-import "../../../navigation/navigation.mojom"
 
 module mojo.launcher {
 
 [Client=LauncherClient]
 interface Launcher {
   Launch(string url);
 };
 
 [Client=Launcher]
 interface LauncherClient {
-  OnLaunch(string handler_url, mojo.navigation.ResponseDetails response_details);
+  OnLaunch(string handler_url, mojo.URLResponse response,
+           handle<data_pipe_consumer> response_body_stream);
 };
 
 }