Mojo: teach launcher about mojo:// URLs.

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 {
+  // Determines the correct handler application that can render a given URL.
+  //
+  // Sometimes this is known statically from the URL (e.g., from its scheme, or
+  // because we already have an application locally that has said it can handle
+  // the URL. Other times, we will actually fetch |url| to examine its
+  // content-type and/or sniff it to determine the correct handler.
   Launch(string url);
 };
 
 [Client=Launcher]
 interface LauncherClient {
-  OnLaunch(string handler_url, mojo.URLResponse response,
-           handle<data_pipe_consumer> response_body_stream);
+  // Called when a handler has been resolved in response to Launch(). Receiving
+  // application should connect to the application at |handler_url| and navigate
+  // it to |view_url|.
+  //
+  // Note: |view_url| might not be the same as the URL that was initially
+  // requested, e.g., in the case of redirects. Applications should always
+  // navigate to view_url, not the initial URL.
+  //
+  // Note: |response| can be NULL in the case where a request was not needed to
+  // determine the correct handler.
+  OnLaunch(string handler_url, string view_url,

[darin (slow to review), 2014/06/20 15:12:37]

The final URL of the redirect chain is also stored in URLResponse.url. That
should always be the same as view_url, right?

[Aaron Boodman, 2014/06/20 16:09:32]

In the case where a request was performed, yes. But a request might not be
performed, so I thought it was better to always pass this URL so clients could
use the API consistently.

I admit it's a bit awkward though. Suggestions welcome.

+           mojo.navigation.ResponseDetails response);
 };
 
 }