serial: Expose connection state for Bluetooth serial ports

Relevant spec change: WICG/serial#197

This CL adds a connected attribute to the SerialPort interface
that exposes the logical connection state of the serial port.
The behavior for Bluetooth serial ports is changed so that the
connect and disconnect events are dispatched when the connection
state of the Bluetooth device changes. The behavior is unchanged
for wired serial ports.

Intent to Prototype: TODO

Bug: 1488031
Change-Id: I34b88246e62202c24eee08ad4a997aff7eadeebb

resources/chromium/fake-serial.js

@@ -346,7 +346,7 @@ class FakeSerialService {
     this.selectedPort_ = null;
   }
 
-  addPort(info) {
+  addPort(info, connected = true) {
     let portInfo = {};
     if (info?.usbVendorId !== undefined) {
       portInfo.hasUsbVendorId = true;
@@ -359,15 +359,18 @@ class FakeSerialService {
 
     let token = ++this.nextToken_;
     portInfo.token = {high: 0n, low: BigInt(token)};
+    portInfo.connected = connected;
 
     let record = {
       portInfo: portInfo,
       fakePort: new FakeSerialPort(),
     };
     this.ports_.set(token, record);
 
-    for (let client of this.clients_) {
-      client.onPortAdded(portInfo);
+    if (connected) {
+      for (let client of this.clients_) {
+        client.onPortConnectedStateChanged(portInfo);
+      }
     }
 
     return token;
@@ -381,8 +384,26 @@ class FakeSerialService {
 
     this.ports_.delete(token);
 
+    record.portInfo.connected = false;
+    for (let client of this.clients_) {
+      client.onPortConnectedStateChanged(record.portInfo);
+    }
+  }
+
+  setPortConnectedState(token, connected) {
+    let record = this.ports_.get(token);
+    if (record === undefined) {
+      return;
+    }
+
+    let was_connected = record.portInfo.connected;
+    if (was_connected === connected) {
+      return;
+    }
+
+    record.portInfo.connected = connected;
     for (let client of this.clients_) {
-      client.onPortRemoved(record.portInfo);
+      client.onPortConnectedStateChanged(record.portInfo);
     }
   }
 

serial/serial_onconnect.https.any.js

@@ -27,3 +27,27 @@ serial_test(async (t, fake) => {
   assert_in_array(event1.target, ports);
   assert_in_array(event2.target, ports);
 }, 'A "connect" event is fired when ports are added.');
+
+serial_test(async (t, fake) => {
+  const eventWatcher =
+      new EventWatcher(t, navigator.serial, ['connect', 'disconnect']);
+
+  // Wait for getPorts() to resolve in order to ensure that the Mojo client
+  // interface has been configured.
+  let ports = await navigator.serial.getPorts();
+  assert_equals(ports.length, 0);
+
+  // Add a disconnected port.
+  const token = fake.addPort({}, /*connected=*/false);
+
+  // The disconnected port is included in the ports returned by getPorts.
+  ports = await navigator.serial.getPorts();
+  assert_equals(ports.length, 1);
+  assert_false(ports[0].connected);
+
+  // Connect the port.
+  fake.setPortConnectedState(token, true);
+  const event = await eventWatcher.wait_for(['connect']);
+  assert_true(event instanceof Event);
+  assert_true(event.target instanceof SerialPort);
+}, 'A "connect" event is fired when a disconnected port becomes connected.');

serial/serial_ondisconnect.https.any.js

@@ -34,4 +34,29 @@ serial_test(async (t, fake) => {
 
   ports = await navigator.serial.getPorts();
   assert_equals(ports.length, 0);
-}, 'A "disconnect" event is fired when ports are added.');
+}, 'A "disconnect" event is fired when ports are removed.');
+
+serial_test(async (t, fake) => {
+  const eventWatcher =
+      new EventWatcher(t, navigator.serial, ['connect', 'disconnect']);
+
+  // Wait for getPorts() to resolve in order to ensure that the Mojo client
+  // interface has been configured.
+  let ports = await navigator.serial.getPorts();
+  assert_equals(ports.length, 0);
+
+  // Add a connected port.
+  const token = fake.addPort();
+  const port = (await eventWatcher.wait_for(['connect'])).target;
+
+  // Disconnect the port but do not remove it.
+  fake.setPortConnectedState(token, false);
+  const event = await eventWatcher.wait_for(['disconnect']);
+  assert_true(event instanceof Event);
+  assert_equals(event.target, port);
+
+  // The disconnected port is included in the ports returned by getPorts.
+  ports = await navigator.serial.getPorts();
+  assert_equals(ports.length, 1);
+  assert_false(ports[0].connected);
+}, 'A "disconnect" event is fired when a connected port becomes disconnected.');