Test that the chooser can initiate device re-discovery.

LayoutTests/bluetooth/requestDevice.html

Index: LayoutTests/bluetooth/requestDevice.html
diff --git a/LayoutTests/bluetooth/requestDevice.html b/LayoutTests/bluetooth/requestDevice.html
index efd10a41f8c48974a0c71fe64f36ebe6332b0641..525d6ab3b83812578788d2e87a4cca0f88cd3d3d 100644
--- a/LayoutTests/bluetooth/requestDevice.html
+++ b/LayoutTests/bluetooth/requestDevice.html
@@ -191,4 +191,39 @@ promise_test(() => {
     filters: [{services: ['generic_access', 'battery_service']}]
   }), 'NotFoundError');
 }, 'Too-strict filters do prevent matching.');
+
+promise_test(() => {
+  testRunner.setBluetoothMockDataSet('SecondDiscoveryFindsHeartRateAdapter');
+  testRunner.setBluetoothManualChooser();
+
+  // Open the chooser, looking for a Heart Rate device.
+  let requestDevicePromise = requestDeviceWithKeyDown({
+    filters: [{services: ['heart_rate']}]
+  });
+
+  // The adapter finds nothing, so we just see discovery start and stop.
+  getBluetoothManualChooserEvents(3).then(events => {
+    assert_array_equals(events,
+                        ['chooser-opened(file:///)',
+                         'discovering',
+                         'discovery-idle',
+                        ]);
+
+    // On the second discovery, the adapter finds the Heart Rate device.
+    testRunner.sendBluetoothManualChooserEvent('rescan', '');
+    return getBluetoothManualChooserEvents(3);
+  }).then(events => {
+    assert_equals(events.length, 3, events);
+    assert_equals(events[0], 'discovering', 'events[0]');
+    let idsByName = new AddDeviceEventSet();
+    idsByName.assert_add_device_event(events[1]);
+    assert_true(idsByName.has('Heart Rate Device'));
+    assert_equals(events[2], 'discovery-idle');
+
+    // Select it and let the test complete.
+    testRunner.sendBluetoothManualChooserEvent('selected',
+                                               idsByName.get('Heart Rate Device'));
+    return requestDevicePromise;
+  }).then(device => assert_equals(device.name, 'Heart Rate Device'));
+}, 'The chooser can restart the BT scan.');
 </script>