Add chrome://usb-internals page for adding and removing test devices.

chrome/browser/ui/webui/usb_internals/usb_internals.mojom

+// Copyright 2016 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 mojom;
+
+struct TestDeviceInfo {
+  string guid;
+  string name;
+  string serial_number;
+  string landing_page;

[Robert Sesek, 2016/08/08 19:11:35]

Should this be a GURL?

[Reilly Grant (use Gerrit), 2016/08/08 20:48:24]

It should but since this interface is being called with user input from
Javascript where a proper URL validator is not available (let me know if I'm
wrong about this) it is easier to do the validation in the browser process.

[Robert Sesek, 2016/08/09 20:42:37]

Is it? It looks like the user input is only for AddDeviceForTesting() and
GetTestDevices() returns this.

[Reilly Grant (use Gerrit), 2016/08/10 01:02:46]

Ah, I see what you mean. I was only looking at AddDeviceForTesting().

+  string allowed_origin;

[Robert Sesek, 2016/08/08 19:11:35]

And should this be a url::Origin?

+};
+
+interface UsbInternalsPageHandler {
+  // Simulate the connection of a new device with the given properties.
+  AddDeviceForTesting(string name,
+                      string serial_number,
+                      string landing_page,
+                      string allowed_origin) => (bool success, string message);
+
+  // Simulate the disconnection of a device added with the function above.
+  RemoveDeviceForTesting(string guid) => ();
+
+  // Retrieves the list of test devices added with this API.
+  GetTestDevices() => (array<TestDeviceInfo> devices);
+};