bluetooth: Implement Service.getCharacteristics

third_party/WebKit/LayoutTests/bluetooth/getCharacteristics/get-same-characteristics.html

+<!DOCTYPE html>
+<script src="../../resources/testharness.js"></script>
+<script src="../../resources/testharnessreport.js"></script>
+<script src="../resources/bluetooth-helpers.js"></script>
+<script>
+'use strict';
+promise_test(() => {
+  testRunner.setBluetoothMockDataSet('HeartRateAdapter');
+  return requestDeviceWithKeyDown({filters: [{services: ['heart_rate']}]})
+    .then(device => device.gatt.connect())
+    .then(gattServer => gattServer.getPrimaryService('heart_rate'))
+    .then(service => Promise.all([
+      service.getCharacteristics('body_sensor_location'),
+      service.getCharacteristics('body_sensor_location')]))
+    .then(characteristics => {
+      let chars1 = characteristics[0];
+      let chars2 = characteristics[1];
+      assert_equals(chars1.length, chars2.length);
+      // TODO(ortuno): getCharacteristics should return the same objects
+      // if they were created earlier.
+      // https://crbug.com/495270
+      for (let i = 0; i < chars1.length; i++) {
+        assert_not_equals(chars1[i], chars2[i]);
+      }
+    });
+}, 'Calls to get the same characteristics should return the same objects.');
+</script>