bluetooth: Add FakeBluetooth interface

third_party/WebKit/LayoutTests/resources/web-bluetooth-test.js

+(() => {
+  let mojo_;
+  let fake_bluetooth_;
+
+  async function getFakeBluetooth() {
+    if (typeof fake_bluetooth_ !== 'undefined') {
+      return fake_bluetooth_;
+    }
+
+    if (typeof loadMojoModules === 'undefined') {
+      throw 'Mojo is required for this API.'
+    }
+
+    mojo_ = await loadMojoModules('fakeBluetooth', [
+      'mojo/public/js/bindings',
+      'device/bluetooth/public/interfaces/test/fake_bluetooth.mojom'
+    ]);
+
+    [mojo_.bindings, mojo_.FakeBluetooth] = mojo_.modules;
+
+    fake_bluetooth_ = new mojo_.FakeBluetooth.FakeBluetoothPtr(
+      mojo_.interfaces.getInterface(
+        mojo_.FakeBluetooth.FakeBluetooth.name));
+
+    return fake_bluetooth_;
+  }
+
+  class FakeBluetooth {
+    constructor() {
+    }
+
+    async setLEAvailability(available) {
+      if (typeof available !== 'boolean') throw 'Type Not Supported';
+      await (await getFakeBluetooth()).setLEAvailability(available);
+
+      // TODO(crbug.com/569709): Remove once FakeBluetooth.setLEAvailability is
+      // implemented in the browser.
+      navigator.bluetooth.requestDevice = function() {
+        return Promise.reject(new DOMException(
+            'Bluetooth Low Energy is not supported on this platform.',
+            'NotFoundError'));
+        };
+    }
+  }
+
+  navigator.bluetooth.test = new FakeBluetooth();
+})();