bluetooth: Add basic scanning to chrome://bluetooth-internals.

chrome/browser/resources/bluetooth_internals/bluetooth_internals.js

Index: chrome/browser/resources/bluetooth_internals/bluetooth_internals.js
diff --git a/chrome/browser/resources/bluetooth_internals/bluetooth_internals.js b/chrome/browser/resources/bluetooth_internals/bluetooth_internals.js
index fe2167d80141459dfd65a757856a545aed7d1530..0dd5390fd3e028a0c0a98907a8027ab05642445b 100644
--- a/chrome/browser/resources/bluetooth_internals/bluetooth_internals.js
+++ b/chrome/browser/resources/bluetooth_internals/bluetooth_internals.js
@@ -50,6 +50,12 @@ cr.define('bluetooth_internals', function() {
   /** @type {devices_page.DevicesPage} */
   var devicesPage = null;
 
+  /** @type {interfaces.BluetoothAdapter.DiscoverySession.ptrClass} */
+  var discoverySession = null;
+
+  /** @type {boolean} */
+  var userRequestedScanStop = false;
+
   function handleInspect(event) {
     // TODO(crbug.com/663470): Move connection logic to DeviceDetailsView
     // when it's added in chrome://bluetooth-internals.
@@ -108,6 +114,26 @@ cr.define('bluetooth_internals', function() {
     });
   }
 
+  function updateStoppedDiscoverySession() {
+    devicesPage.setScanStatus(devices_page.ScanStatus.OFF);
+    discoverySession.ptr.reset();
+    discoverySession = null;
+  }
+
+  function setupAdapterSystem(response) {
+    console.log('adapter', response.info);
+
+    adapterBroker.addEventListener('adapterchanged', function(event) {
+      if (event.detail.property === 'discovering') {

[dpapad, 2017/01/05 23:30:33]

Is there a need for two separate if conditions? How about the following?

if (event.detail.property === 'discovering' &&
    !event.detail.value && !userRequestedScanStop && discoverySession) {
  ...
}

[mbrunson, 2017/01/06 01:18:56]

Done.

+        if (!event.detail.value && !userRequestedScanStop && discoverySession) {
+          updateStoppedDiscoverySession();
+          Snackbar.show(
+              'Discovery session ended unexpectedly', SnackbarType.WARNING);
+        }
+      }
+    });
+  }
+
   function setupDeviceSystem(response) {
     // Hook up device collection events.
     adapterBroker.addEventListener('deviceadded', function(event) {
@@ -124,6 +150,44 @@ cr.define('bluetooth_internals', function() {
 
     devicesPage.setDevices(devices);
     devicesPage.pageDiv.addEventListener('inspectpressed', handleInspect);
+
+    devicesPage.pageDiv.addEventListener('scanpressed', function(event) {
+      if (discoverySession && discoverySession.ptr.isBound()) {
+        userRequestedScanStop = true;
+        devicesPage.setScanStatus(devices_page.ScanStatus.STOPPING);
+
+        discoverySession.stop().then(function(response) {
+          if (response.success) {
+            updateStoppedDiscoverySession();

[dpapad, 2017/01/05 23:30:33]

Is the |userRequestedScanStop| really necessary? My understanding is the
following:

calling discoverySession.stop() will trigger an 'adapterchanged' event, which
already calls updateStoppedDiscoverySession(). Here we use the boolean to
prevent that codepath, but also we call that method manually. Can't we just
always rely on 'adapterchanged' listener to call updateStoppedDiscoverySession?

[mbrunson, 2017/01/06 01:18:56]

It's because of the 'adapterchanged' event that I added the
|userRequestedScanStop|. In every case where the scan status of the adapter
changes, the 'adapterchanged' event is fired.

This includes cases where the user did not explicitly request that scanning
should be stopped (e.g. there's some outside program that stopped it or some
hardware malfunction). I wanted a way to differentiate between these two cases
to alert the user that their discovery session was killed without their consent.

+            userRequestedScanStop = false;
+            return;
+          }
+
+          devicesPage.setScanStatus(devices_page.ScanStatus.ON);
+          Snackbar.show(
+              'Failed to stop discovery session', SnackbarType.ERROR);
+          userRequestedScanStop = false;
+        });
+
+        return;
+      }
+
+      devicesPage.setScanStatus(devices_page.ScanStatus.STARTING);
+      adapterBroker.startDiscoverySession().then(function(session) {
+        discoverySession = session;
+
+        discoverySession.ptr.setConnectionErrorHandler(function() {
+          updateStoppedDiscoverySession();
+          Snackbar.show('Discovery session ended', SnackbarType.WARNING);
+        });
+
+        devicesPage.setScanStatus(devices_page.ScanStatus.ON);
+      }).catch(function(error) {
+        devicesPage.setScanStatus(devices_page.ScanStatus.OFF);
+        Snackbar.show('Failed to start discovery session', SnackbarType.ERROR);
+        console.error(error);
+      });
+    });
   }
 
   function setupPages() {
@@ -154,7 +218,7 @@ cr.define('bluetooth_internals', function() {
     adapter_broker.getAdapterBroker()
       .then(function(broker) { adapterBroker = broker; })
       .then(function() { return adapterBroker.getInfo(); })

[dpapad, 2017/01/05 23:30:33]

The info returned by this call is never used by setupAdapterSystem(). Can this
call be removed?

[mbrunson, 2017/01/06 01:18:56]

The info returned is currently logged to console because there's no associated
UI for this piece of data. It will be used in the next patch [1][2], so I don't
want to remove this just to add it right back.

[1] https://codereview.chromium.org/2567983007/
[2]
https://codereview.chromium.org/2567983007/diff/180001/chrome/browser/resourc...

-      .then(function(response) { console.log('adapter', response.info); })
+      .then(setupAdapterSystem)
       .then(function() { return adapterBroker.getDevices(); })
       .then(setupDeviceSystem)
       .catch(function(error) {