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

chrome/browser/resources/bluetooth_internals/bluetooth_internals.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * Javascript for bluetooth_internals.html, served from
  *     chrome://bluetooth-internals/.
  */
 
 // Expose for testing.
@@ skipping 32 matching lines @@
 
   /** @type {!Map<string, !interfaces.BluetoothDevice.DevicePtr>} */
   var deviceAddressToProxy = new Map();
 
   /** @type {!device_collection.DeviceCollection} */
   devices = new device_collection.DeviceCollection([]);
 
   /** @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.
     var address = event.detail.address;
     var proxy = deviceAddressToProxy.get(address);
 
     if (proxy) {
       // Device is already connected, so disconnect.
       proxy.disconnect();
       deviceAddressToProxy.delete(address);
@@ skipping 38 matching lines @@
 
       devices.updateConnectionStatus(
           address, device_collection.ConnectionStatus.DISCONNECTED);
 
       var deviceInfo = devices.getByAddress(address);
       Snackbar.show(deviceInfo.name_for_display + ': ' + error.message,
           SnackbarType.ERROR, 'Retry', function() { handleInspect(event); });
     });
   }
 
+  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) {
       devices.addOrUpdate(event.detail.deviceInfo);
     });
     adapterBroker.addEventListener('devicechanged', function(event) {
       devices.addOrUpdate(event.detail.deviceInfo);
     });
     adapterBroker.addEventListener('deviceremoved', function(event) {
       devices.remove(event.detail.deviceInfo);
     });
 
     response.devices.forEach(devices.addOrUpdate, devices /* this */);
 
     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() {
     sidebarObj = new window.sidebar.Sidebar($('sidebar'));
     $('menu-btn').addEventListener('click', function() { sidebarObj.open(); });
     PageManager.addObserver(sidebarObj);
     PageManager.addObserver(new PageObserver());
 
     devicesPage = new DevicesPage();
     PageManager.register(devicesPage);
 
     // Set up hash-based navigation.
     window.addEventListener('hashchange', function() {
       PageManager.showPageByName(window.location.hash.substr(1));
     });
 
     if (!window.location.hash) {
       PageManager.showPageByName(devicesPage.name);
       return;
     }
 
     PageManager.showPageByName(window.location.hash.substr(1));
   }
 
   function initializeViews() {
     setupPages();
 
     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) {
         Snackbar.show(error.message, SnackbarType.ERROR);
         console.error(error);
       });
   }
 
   return {
     initializeViews: initializeViews
   };
 });
 
 document.addEventListener(
     'DOMContentLoaded', bluetooth_internals.initializeViews);